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Several people mentioned that the external trigger input (TTL) does not work on the DRS4 Evaluation Board Rev. 1.1. This is not true. The requirement however is that the input signal must exceed approximately 1.8V. Since the input is terminated with 50 Ohms, not all TTL drivers may deliver enough current to exceed this threshold. To verify this, the trigger signal can be monitored with an oscilloscope at test point J24. Only if the input signal exceeds 1.8V, the signal will be seen at J24 and correctly trigger the FPGA. If the TTL driver is too weak, the termination resistor R9 can be optionally removed, but care should then be taken that reflections in the trigger input do not cause double triggers. The locations of the tap point for the input signal, the termination resistor R9 and the tap point J24 after the input level converter U5 are shown in this image:

Another tricky issue comes from the fact that the external TTL trigger and the comparator are in a logical OR. So if the comparator level is set such that the signal is always over the threshold, the trigger is always "on" and the TTL trigger does not have any effect. It is therefore necessary to set the analog trigger level to a very high value in order to make the TTL trigger work. 

 Please note the new datasheet Rev. 0.8 available from the DRS web site. It fixes the label of pin #76, which was AGND but is actualy AVDD. The input IN8+ is located at pin #20 and not at pin #19 as described in the old table 2.

Many applications using the DRS4 need to measure fast rising signals, like for PMTs or MCPs. This short note shows the minimal rise-times which can be measured with different input signal conditioning.

Evaluation Board

The evaluation board contains four passive transformers ADT1-1WT from Mini-Circuits to convert the single-ended input signal into a differential signal. Although these parts are rated 800 MHz bandwidth (-3dB), they have hard time to drive the DRS4 inputs. This is because at high frequencies the input impedance of DRS4 becomes pretty small (~20 Ohm at 500 MHz) due to its capacitive nature. Furthermore, each transformer drives two DRS4 inputs (channel cascading) which enhances this problem by a factor of two. We made a quick test sending a signal to the evaluation board with a rise time of 277ps and a fall time of 280ps. The result measured with the evaluation board is seen here:

The measured rise-time (10%-90%) is only about 2ns. Disconnecting the second channel from each transformer improves this situation a bit:

so the rise-time comes down to ~1.6ns.

Active ADA4937 driver

We tested the behavior using an active buffer ADA4937 to replace the passive transformer. Without the DRS4 connected to this buffer, we measured with the oscilloscope a rise time of 408ps and a fall time of 644ps. When we connect the DRS4 (single channel), this values increase to 702ps (rise) and 1400ps (fall), all measured with a differential oscilloscope probe (WL300 4 GHz Bandwidth, LeCroy 7300A, 3 GHz Bandwidth). In this case the rise time seen by the DRS4 is wieth ~700ps accordingly shorter:

(The signal was not properly terminated and therefore we have a small overswing). 

Conclusion

To obtain an optimal rise-time measurement, the design of the input stage is rather important. A fast active driver seems to do a better job than a passive transformer (which was used on the evaluation board for power reasons). Connecting only one DRS4 channel to the input improves the rise-time measurement significantly. If channel cascading is still needed, a design should use one driver for each channel, and not driver two or more DRS4 inputs from a single buffer.

If anybody comes up with an even better input driver, I'm happy to publish the results here.

This is a quick notification to all users of the current DRS4 evaluation board.

As you all know, the DRS4 chip needs some calibration for each individual cell which corrects the offset and the non-equidistant width in time. While the first evaluation boards have been shipped without this calibration, the current version of the software implements a full amplitude and timing calibration. The offset correction reduces the noise of the board by almost an order of magnitude to below 1 mV RMS. The timing calibration using an on-board reference clock allows a timing accuracy in the order of 10 ps. To illustrate that the following two pictures show a reference clock signal before and after timing calibration:

The integral temporal nonlineairy at 5 GSPS before timing calibration is about 600 ps as can be seen by the jitter of the overlaid waveforms.

In order to do a timing calibration, the firmware revison 13297 or later is required. The current software package 2.1 contains an updated firmware, but unfortunately one needs a Xilinx download cable to flash this new firmware (see http://drs.web.psi.ch/download/ under "Software Versions"). If some people want an update but do not want to buy such a cable, we offer a free update at our institute (just the postage has to be paid). The old evaluation board (Rev. 1.0, plastic housing) can unfortunately not be updated.

After the offset calibration is made, there are small (~20mV) short spikes left. They probably come from some cross-talk between the USB interface and the analog part of the board. This is currently under investigation. If new updates become available, they will be announced in this forum.

April 27th, 2009,

Stefan Ritt

Maybe some of you have experienced that the DRS4 chip can get pretty hot after power up. After it's initialized the first time, the power consumption goes back to normal. I finally found the cause of this problem and have a remedy. Here is the new paragraph from the updated data sheet:

During power-up, care has to be taken that the DENABLE and DWRITE signals are low. If not, the domino wave can get started before the power supply voltages are stable, which brings the DRS4 chip into a state where it draws a considerable amount of current and heats up significantly. This can be problematic if the signals are directly generated by a FPGA, since most FPGAs have internal pull-up resistors which get activated during the configuration phase of the FPGA. In such a case, the DENABLE and DWRITE signals should be connected to GND with a pull down resistor. This resistor should be much smaller than the FPGA pull-up resistor in order to keep the signals close to GND during the FPGA configuration. A typical value is 4.7 kOhm.

The attached schematics shows the location of the two required resistors.

The current version of the DRS readout example program drs_exam.cpp has two problems:

1. The sampling frequency cannot be changed, it will always stay in the region around 5 GSPS
2. The waveform obtained by GetWave is rotated such that the first DRS cell corresponds to the first array bin

Both problems have been fixed and the fix will be contained in an upcoming software release.

It has turned out that the stability of the AVDD and DVDD power supplies for the DRS4 are very critical. On the evaluation board I use a REG1117-2.5, on our VME board I use a ADP3338-2.5 for the DVDD power supply. When the domino wave is started, the power consumption of the DRS4 chip jumps up by ~40 mA, which has to be compensated by the linear regulator. Following screen shot shows what happens:

The blue trace is the DWRITE signal indicating the sampling phase when high. The yellow is the SRCLK showing when the readout takes place. The pink is now the DVDD power. It can be clearly seen that there is a dip of ~50 mV when the domino wave starts, a positive dip when it stops and another smaller dip when the readout starts. This causes strange effects: If the trigger arrives during the first dip, the actual sampling takes place when the DVDD is ~50 mV smaller, which leads to a baseline shift of a sampled 0V DC input voltage of about the same amount (-50 mV).

The obvious improvement is to put a huge capacitor on the power supply, but that does not help much:

The dip gets a bit smaller, but it's still there. So a better solution would be to use a faster LDO regulator. Please take care of this if you plan a new design.

Furthermore, I believe that the chip internally has some "warmup" phase, where the die heats up a bit when the additional 40 mA are drawn. So a "good" solution is to wait some time after starting the domino wave until one allows for triggers. Tests showed that a few milliseconds are necessary to keep the baseline shifts below a few millivolts. This of course decreases the dead time of the system significantly, so one has to choose the proper balance between increase dead time and increased base line shift. On some applications where a baseline shift is not an issue, one could opt for the minimum dead time.

It turned out that the VDD switch off speed plays some important role. On our VME board, we have a linear regulator, then a 4.7 uF capacitor, then the DRS4 chip (DVDD and AVDD). When switching off the VME power, it takes quite some time to discharge the 4.7 uF capacitor, since the DRS4 chip goes into a high impedance mode if VDD < ~1V. This gives following VDD trace:

Rising edge is power on, falling edge is power off. Note the horizontal time scale of 2 s/div. So to get below 0.3 V or so, it takes up to 30 seconds. If the power is switched back on when AVDD is above 0.3V, the DRS4 chip can get into a weird state, where probably many domino waves are started and the chip draws an enormous amount of current. Typically the linear regulator limits the current, so the 2.5V drops to ~1.5V, and the board is not working. If people are aware of this and always wait >30sec. before turning the power on again, this is fine, but people might forget.

So the solution is to put a resistor (typically 100 Ohm to 1 kOhm) parallel to the 4.7 uF capacitor in order to have some resistive current load of a few mA. The discharge then looks like this:

Note the horizontal scale of 10ms/div. So after 30 ms AVDD is discharged and powering on the chip again does not do any harm. The same should be done to DVDD.

For the users using a Macintosh,

after several hours the Evaluation Board is working  on my Macintosh (intel).

1) install the development package with xcode, its on the OS X installation DVD

2) install the libusb binary from http://www.ellert.se/twain-sane/

3) modify the makefile  for compiling drs_exam (attached) afterwards it's running perfect!

best,

Armin

Hello Mr. Stefan Ritt

          In DSR4 DATASHEET Rev.0.8 Page13, I noticed you metioned the samping should occur after 38 ns after the rising edge of SRCLK when the multiplexer is used. So what is suggested value(delay time between sampling and the rising edge of SRCLK) for the parallel mode,in which the multiplexer is not used?

          Best wishes!

                                                       Jinhong Wang

The clock-to-output delay is the same if one uses the multiplexer or not. I found however that in most cases the delay of 38 ns needs some fine tuning to get optimal performance. So I typically use a shifted clock generated by the FPGA clock manager with a programmable delay (+-5 ns for Xilinx) and optimize this in the running system.

Dear Mr. Stefan Ritt.

         Thank u for your timely response on "DSR4 Full Readout Mode", I received it from Professor Qi An, who is my PhD supervisor.

        I am currently going through the DRS4 datasheet. Well, can you give some specification on the usage of "BIAS" pin of DRS4? It is just metioned in the datasheet as bias of internal buffer. What is the internal buffer exactly reffered to here? The MUXOUT buffer of channel 8 or else? Does it have some relationship to O_OFS? I mean, if the reference voltage to BIAS is changed, how will the output be influenced?

       Looking forward to hearing from you soon.

                                                                       Jinhong Wang

                                                                    Fast Electronics LAB. of University of Science and Technology of China.

"internal buffers" are all internal operational amplifiers in the DRS4 chip. Every OPAMP needs a bias (just look it up in any electronics textbook), which determines the linearity and the speed of the OPAMP. When designing DRS4, I was not sure if the required BIAS voltage changes over time, or between chips, so I made it available at a pin, which is a common technique in chip design. But it turns out now that this voltage is not very critical, so just keeping the pin open will work in most cases. 

No. It shifts about ROFS-0.25V. So only if ROFS=1.55V, the shift will be 1.3V.

Just read the datasheet under "ANALOG OUTPUTS". I'm sorry if I did not describe this clearly, but the U+ voltage is fixed (only dependent on ROFS), and U- can be calculated using Uofs as written in the datasheet. 

OUT+ is 0.8V~1.8V, OUT- is 2*Uofs-OUT+. So you can only change the OUT- level, not the OUT+ level. 

                                                                                                            Fig.1        typical dimension of QFN package

Above is the typical dimension specification for QFN package. I cann't find the corresponding "T1" as in Fig.1 in the DRS4 documents, nor any of the tolerance of the dimensions, which are usually expressed in the form of  a range between a min. value and a max. value.

So will you specify the dimension of "T1" and "W1", and the dimension tolerance of them?

Thanks and best wishes!

                                                                               Jinhong Wang       University of Science and Technology of China

Please find attached the complete dimensions.

Dear Mr. S. Ritt

     The following is my confusion about the trigger of DRS4. It mainly concertrates on the generation of trigger signal to stop DRS4 sampling process for readout of sampled waveform.

     As metioned in the datasheet of DRS4, the chip samples the analog input every domino sampling period.  After finished sampling a waveform, the sampling process can be stoped by lowering the DWRITE while keeping DENABLE high. But the analog input is asychronous to the Domino CLK.  Then, how can we know when to  stop the domino sampling process to read out the sampled waveform? Of course, a trigger can be used. But from my present knowledge of DRS4, trigger can only be generated from analog input. Analog input is splited into two channels, one to DRS4 analog input, the other to FPGA as the trigger. However, splitting analog inputs increases the system design complexity, and may lower the total performace. So what is your suggestion?

    In our system, there are 8 analog inputs to a signal DRS4 chip, the outputs of DRS4 chip are connected to an 8-channel 14 bit ADC ( AD9252). It wold be kind of you to inform me about the most applicable approach for readout of DRS4 sampled wavefrom.

   Best regards.

   Sincerely,

   Jinhong Wang (wangjinh@mail.ustc.edu.cn)

Indeed you have to make an external trigger. The evaluation board uses the "transparent mode" of the DRS4 to "mirror" the input signal at the output, then puts a comparator there. The schematics of the evaluation board is in the manual. This does then not degrate the analog performance. You can of course also split the signal at the input, this will only add a minor additional load to the input signal, since the load of the DRS4 chips itself is much bigger than that of any comparator.

An alternative is to turn on the transparent mode and continuously digitize all 8 outputs with your AD9252. Then you make the trigger purely digital in your FPGA. You can put there a comparator, or even more complex logic like multiplicity etc. Note however that this causes some latency, since the ADC has a pipeline which is quite long, so you have to buffer the latency of your trigger in the analog window of the DRS4 sampling cells. Like if you run the DRS4 at 1 GSPS, you can accomodate 1024 ns of sampling depth, which is good for maybe 500 ns of trigger latency plus 500 ns of the waveform of interest.

Thank you. The transparent mode can be really helpful. Can you provide me in more details of the chip's transparent mode? I am still confused about the following aspects.

I notice that DRS4 samples the analog wave in the way "clear before write", and in the transparent mode, there will be certain delay before the trigger logic stops the sampling process. So,does it mean that the waveform recording process per Domino sampling cycle will not degrade the amplitude of the analog signal? Hence, for two idential analog inputs, one with a trigger latency of 500 ns and the other of 510 ns, the sampled waveform is identical, what differs is the starting number of the first active sampling cell, where the reading process considered to be started.   Is that right? Looking forward to your insight.

Best regrads.

Sincerely,

         Jinhong Wang (wangjinh@mail.ustc.edu.cn)

The amplitude of the analog signal is not degraded by the transparent mode, since the signal is buffered on the chip, and the output of this buffer is send off the chip. The waveform digitizing of course requires quite some current to charge up all capacitors, so there is  maximum current of ~1mA for 5 GSPS. If you only have a weak signal source, your bandwidth might be limited by that. On the evaluation board for example we use passive transformers to produce the differential input signal from a single-ended signal. Although the transformers are rated 1 GHz Bandwidth, we only achieve 200 MHz with the passive transformers. By using active high speed differential drivers, you can get about 700 MHz right now.

If you have two channels with 500 ns and 510 ns trigger latency, there is no difference in the "domino stop position" since there is only one domino circuit per chip which can be stopped. So the stop position is the same for all eight channels on a chip. 

 So you mean there is an analog buffer per channel? The analog signal is buffered there, before entering the sampling cells? Then, when will the buffer content be released and cleared? How shall I handle "Dwite" and "Denable" during a complete operation when an analog signal arrives in the transparent mode? I cannot find more information beyond the datasheet,  a detailed description of the transparent mode (and the analog buffer, if possible) will be really helpful for me.

Best,

Sincerely,

Jinhong Wang (wangjinh@mail.ustc.edu.cn)

There is one analog buffer per channel at the output, as indicated on the FUNCTIONAL BLOCK DIAGRAM of the datasheet. The section ANALOG INPUTS clearly states that the input signal has to load directly the sampling capacitors.

All other people using the chip so far correctly understood these things so far, so I believe more information beyond the datasheet is not necessary. I believe you have a principal problem of understanding, which can hardly be clarified by email. Best would be if you directly call me, I can then explain things to you.

 Dear Mr. S. Ritt

       i am Ms. student , am working with your DRS4 board to calculate the time of flight of the cosmic particle which passes trough  the hodoscope . i see the signals at scope , which is negative (i don't want to take positive side of the signal).

       i am using your drs_exap.cpp file to  take the data, i set the analog trigger source , threshold level is negative, like this(b->SetTriggerLevel(-30, true) ); but the exam file also registers the positive side of signal (i think  that is spike or internal reflection), is it possible to eliminate this spike? Also i want to register  the data just after the threshold value, but that is always triggered, i think that caused from the mode. Is it possible to set the trigger mode to normal in exam file?,and  how can i do that?

Best regards.

Sincerely,

 Ali YILMAZ (ali.yilmaz@roma1.infn.it)

Please note that SetTriggerLevel(level, polarity) needs "level" in volts, not millivolts, so you need SetTriggerLevel(-0.3, true). The trigger mode is not specified with any library call, but depends on what your program does. If you always poll on IsBusy(), then you are already in "normal" mode. The auto mode can only be achieved on the user application level by doing an "artifical" trigger by calling SoftTrigger() if there are no hardware triggers for a certain time. 

Hi Stefan,

    I have an old-version DRS4 evaluation board which doesn't have the latest firmware. I tried to flash the drs_eval1.ipf boundary scan chain into the XCF02S PROM with Xilinx IMPACT, and the firmware seemed to go through into the PROM. However, when I started the DRS command line interface to test the firmware it kept on reporting errors like

musb_write: requested 10, wrote -116, errno 0 (No error)

musb_read error -116

musb_write: requested 10, wrote -22, error 0 (No error)

musb_read error -116

and so on. Finally the program made a dumb recognition of the board as

Found mezz. board 0 on USB, serial #0, firmware revision 0

Do you have any idea which caused this problem? Thanks!

A firmware update requires a power cycle of the evaluation board. Have you tried that? I attached for you reference the current drs_eval1.mcs file, which is meant to go into the XCF02S PROM. There were recent changes also in the DRS library, and I'm not sure if yous if recent enough. So I put also the current C files which go with the firmware. They contain also some improvements which should reduce the intrinsic noise of the board.  

hello i am an student and i want to do my final project with drs4 board and i really can´t find how to open waveform file and how can i save or opened many of them quickly.

if you can tell me how i will be very grateful.

thanks,

kind regards.

There is no built-in possibility to open waveform files, you have to write your own programs to do that. 

I have saved some waveforms using the oscilloscope application in both binary and xml.  I can see that the xml file gives me proper data values but when I try to read the binary file using IDL, it does not seem correct.  This is a screen shot of the pulse I saved:

But when I open the binary file in IDL using:

data = uintarr(1024)       ;unsigned integer array
readu,lun1,data
free_lun,lun1
close,lun1

;Convert bits to Volts
data=data*0.000015259-0.5        

window,0,xs=512,ys=512
plot,data[*]

I get:

It looks like the pulse is there but there is something corrupting the data only in binary form.  Is there a setting that may not be correct?

Thanks, Ron

Yes, but you have to recompile the oscilloscope application. Find following line in the source file DOFrame.cpp:

            m_WFfd = open(filename.char_str(), O_RDWR | O_CREAT | O_TRUNC | O_TEXT, 0644);

and replace it with

            m_WFfd = open(filename.char_str(), O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0644);

 that fixes the problem. To compile the program, you need MS Visual C++ and you have to install the vxWidgets library. Let me know if you have any problem with that.

Anyhow I plan a major software update soon (weeks), which not only fixes this problem, but also reduces the noise considerably by doing a kind of two-fold calibration.

- Stefan

Hello,

may I draw your attention to the upcoming Real Time Conference 2010, taking place in Lisbon, Portugal, May 23rd to May 28th, 2010.

http://rt2010.ipfn.ist.utl.pt/

Several groups which are developing DRS4 electronics will come to this conference and present their work, so it will be a good opportunity to exchange ideas and experiences. There will also be a short course on digital pulse shape processing, which is highly relevant for our field.

Looking forward to see you in Lisbon,

    Stefan 

Hi Stefan,

    in the latest DRS4 datasheet I only saw your data of the DRS4 PLL locking time for 6GSPS sampling speed, with other rows "TBD". Have you tried those lower frequencies? According to the datasheet I think the PLLLCK should be stabily low when the PLL is locked; am I right? However when I try my design with the DRS4 chip and feed the reference clock signal at 0.5MHz or 2MHz, the PLLLCK I get can never stabilize. There could be some problem in the PCB circuit connection, but I want to confirm with you since I'm confused with those "TBD" blanks.

    Thanks a lot!

The locking time is typically 20-30 cycles of the external reference clock, I will update the numbers in the datasheet soon. I attached a screenshot of the chip when starting up at 1 GHz (0.5 MHz REFCLK), so you can see the behaviour. The upper curver is the DTAP signal, the lower curve the PLLLCK signal. As you can see, the PLLLCK signal is not purely digital. Actually it's a simple XOR between the REFCLK and the DTAP signal, so you need an external 4.7nF capacitor to "integrate" this signal. Without this capacitor, you would see small negative spikes whenever there is s small phase shift between the DTAP and the REFCLK signal. Have a look at your DTAP signal, is it in phase with the REFCLK? 

Thanks! I see. The capacitor is important. However I'm a little confused... If PLLLCK=DTAP XOR REFCLK, shouldn't it integrate to low instead of high when the two clocks are in phase? I must have some misunderstanding here. So if we ignore any realistic complexity and assume DTAP is perfectly locked with REFCLK, will PLLLCK be always low or high? I'm sorry I do not know how the DRS internal PLL and its input/output work...

Actually the XOR is followed by an inverter, so it will integrate to high if the two clocks are in phase. 

 Got it. Thank you! By the way I have another question: when the default operation mode of the DRS4 chip is used, i.e. WSRIN is fed internally to WSROUT, at the external pins is it necessary to leave the WSRIN open? Or any input through the pin will not affect the Domino wave running? Also I observe that WSROUT will be always low when the chip is running in this mode; is it the supposed behavior?

If the WSRin is fed internally to WSROUT, then the level of the WSRIN pin does not matter, it's just disconnected. You can leave the pin open without problem. WSROUT is however active, so you can observe the internal state of the write shift register. In the default configuration (8x1024 sampling cells), all 8 channels are active all the time, so the WSR is loaded with ones. The inverter at the output then makes all zeros from this. If you configure the chip as 4x2048 cells, then you will observe switching bits at WSROUT. 

 Sorry; WSROUT also has an inverter? Actually I have one more stupid question about the shift registers: when we assert the address bits to operate on one shift register, e.g. WSR, we use SRIN to give input and SROUT to read output; but how does the shift register know whether we're reading or writing? Or it will just receive input from SRIN and give output at SROUT at the same time?

Thank you so much!

Actually I double checked the schematics, WSROUT has NO inverter at the output. So the output should be always one in a 8x1024 channel configuration.

Concerning the read/write you are right. On each clock cycle, SRIN will be shifted into the first bit, and the last bit will be visible at SROUT.

Hi Stefan,

    I read in the datasheet that every time after power up the Domino wave in DRS4 needs to be started and stopped once to initialize the Domino circuit. However in your firmware it seems the chip immediately goes into the idle state after reset. Is that Domino circuit initialization really necessary?

    Also an aside question: in your firmware the readout process has the SRCLK sent to DRS4 only about 200ns later after RSRLOAD gets asserted instead of immediately following RSRLOAD. Is there any reason for that?

    Thanks a lot!

The start/stop requirement is obsolete and has been replaced by  elog:10. I need to update this in the datasheet. The delay between the RSRLOAD and the SRCLK has the following reason: On the RSRLOAD the first sampling cell is output to the chip and to the ADC. This can sometimes be a rather high swing, which needs some time to settle, and some warm-up for the output driver. But actually I never really measured it, so it's there just as a safety margin. But I would encourage you to try to reduce this time and see it the first few bins of the readout change in offset.

Hi Stefan,

    thanks to your help I can now successfully keep the Domino wave running at a stable frequency and maintain the channel cascading information in the Write Shift Register. (Since you told me WSR always reads and writes at the same time, I think I need to rewrite the information back every time after reading out from WSR to decide from which channel my data come, don't I?)

    However I'm still having difficulty in reading out from the DRS cells. I use the ROI readout mode and assume as long as I give a pulse on RSRLOAD the data will come out one by one. However, what I get is just a constant with some noise, which seems I'm always reading from the same cell. Actually I'm not very clear about how it works. What's the mechanism for RSRLOAD  and do I have to initialize the Read Shift Register to use the ROI mode? Also I read in the datasheet that WSROUT will give RSR output when DWRITE is low. Sometimes I see some random bits from this output and sometimes I see all zero's. What is the reasonable output I should see from WSROUT, say, when I'm running in the transparent mode with DWRITE low?

    Thank you very much!

Hi Stefan,

    I tried again and confirmed the problem... In the full readout mode I could successfully read out all the data, but in the ROI mode if I naively apply a pulse at RSRLOAD the results are not right. Is there anything I should be careful about in the ROI readout mode?

    Thanks!

Yes you do. But if you have WSRLOOP=1 in the config register, this is done automatically. So the SR output is visible at the pin and will be fed back into the input.

That's not correct. Have a look at Figure 14 of the datasheet. Do you see a single RSRLOAD pulse or many? There is only one RSRLOAD pulse to initialize the readout shift register, then the cells are clocked by SRCLK pulses. 

A single RSRLOAD pulse loads the RSR with a "1" at the domino stop position and "0" in all other places. A pulse on SRCLK shifts this "1" down the RSR. When it arrives at cell #1023, it will be visible for one clock cycle at WSROUT. The "double" functionality of WSROUT has the following background: Assume you use channel cascading 2x2048. Now the domino wave stopps in cell 1020 of the first channel for example. You have to read cells 1020,1021,1022,1024 of the first channel, then you continue with 0,1,2 on the second channel. But how do you know that you have to switch channels after the first four clock cycles? The SROUT output encodes the stop position (in this case 1020), but it needs 10 clock cycles before the information is available, so you don't have it after four cycles. That's where WSROUT comes into play: Since it outputs RSR bit by bit, it will show three "0", then a "1", when you are at cell 1023. Then you know that you have to switch channels immediately. That's why I output RSR via WSROUT if DWRITE is low.

Hi Stefan,

    I read in the DRS datasheet that the input bandwidth if 950MHz. However, it also says the output bandwidth in the transparent mode is 50MHz. Since in the transparent mode the input is routed to the output, does it mean the input bandwidth also gets reduced in the transparent mode? I don't know how the transparent mode works inside the chip of course, but this value would be important since if the hardware discriminators are connected to the output of DRS, we have to always work in the transparent mode.

    Thanks!

In transparent mode, the input signal also gets routed to the output, where it goes through an output buffer, which limits the bandwidth to about 50 MHz, but only for the output. The effective bandwidth to the sampling cells is not changed. Please note however that the 950 MHz are for the "chip only". We measured this by keeping the input amplitude from a function generator constant at the input pin of the chip (measured with a high speed oscilloscope). Since each signal source has a non-zero impedance, the signal tends to "shrink" at high bandwidth, and we had to adjust the level of the function generator to keep the amplitude constant at high frequencies. If you do a realistic input stage with the THS4508 for example, the achievable bandwidth will be around 800 MHz.

Hi Stefan,

    in the DRS4 datasheet I read that the optimal frequency for SRCLK is 33MHz. However in the evaluation board firmware SRCLK is toggled at rising edges of the internal 33MHz clock, i.e. the frequency of SRCLK itself is 16.5MHz instead. Is that frequency better than 33MHz?

    Thanks!

The reason for the 16.5 MHz is the following:

After each block of 32 bins, the DRS4 chip switches an internal segment, which causes some small spike at the analog output of the chip. This spike is a bit wider than 30ns, so if everything is digitized with 33 MHz, then you see small spiked each 32 cells. The appropriate solution would be to modify the firmware to digitize all cells with 30ns (33 MHz) and all cells with the spike with ~50 ns (20 MHz). If you do the ROI readout mode, you don't know for the first 10 cells if one of them belong to this class, since the cell address takes 10 cycles to be read out. So you would first have to read 10 cells, and then if you realize that one of them is one of the problematic ones (cell number modulo 32 is zero), you have to re-read the first 10 cells, and digitize the problematic cell with a longer settling time. Now this is a bit complicated to implement in the firmware, so I was just too lazy to do it and decided to digitize everything with 16.5 MHz. But if you are worried about the dead time, you should consider implementing the mentioned algorithm. 

 Thanks! The suggested algorithm looks promising. However, if the spikes take place only for those specific cells, is it possible to absorb them into the offset calibration?

No, since they are not constant. The bus segments charge up between readouts with a time constant of about 0.5s. So if you do the readout with 1Hz event rate and with 100Hz event rate, the peaks will differ by a factor up to 10, so a constant offset correction cannot take care of that.

Hi Stefan,

    in the datasheet it says at 6GSPS the typical loop filter parameters are 220Ω, 2.2nF and 27nF. If I want to run the Domino wave nominally at 1GHz, i.e. with a reference clock frequency around 0.5MHz, is there any recommended loop filter configuration? Is the setup of the evaluation board, that is, 220Ω, 3.3nF and 33nF an optimal choice?

    Thank you very much.

The setup of the evaluation board is a good compromise which runs between 1 GHz and 5 GHz. Unfortunately I never found the time to investigate this in more detail. So if someone is willing to measure settling time and phase jitter with various combinations of R, C1 and C2, I'm more than happy to include this into the datasheet. 

Hi all

it is possible to use the evaluation board like a counter?

I'm interested in the arriving time of all self trigger event in to a channel.

the input signal are 2V TTL of 10 ns at 50ohm, and the time acquisition window is 1 second.

can someone help me?

thanks in advance,

Lorenzo

The evaluation board is as good or bad as an digital oscilloscope to work like a counter. At 1 GSPS, you have a window of one microsecond, which is certainly too short for your application. 

Hi Stefan,

    when I sample a constant input with the DRS 4 chip, there was a baseline variation showing up as a saw-tooth pattern which grows with the absolute value of the differential input. Do you think this is the kind of baseline variation mentioned in the evaluation board manual, i.e. coming from clock jitter in ADC sampling?

    Thanks a lot!

Please post an oscilloscope screenshot here and I can tell you. 

Several people asked for s simple application to guide them in writing their own application to read out a DRS board. Such an application has been added in software revions 2.1.1 and is attached to this message. This example program drs_exam.cpp written in C++ does the following necessary steps to access a DRS board:

• Crate a "DRS" object and scan all USB devices
• Display found DRS boards
• Initialize the first found board and set the sampling frequency to 5 GSPS
• Enable internal trigger on channel #1 with 250 mV threshold
• Start acquisition and wait for a trigger
• Read two waveforms (both time and amplitude)
• Repeat this 10 times

I know that we are still missing a good documentation for the DRS API, but I have not yet found the time to do that. I hope the example program is enough for most people to start writing own programs. For Windows users (MS Visual C++ 8.0) there is a drs.sln project file, and for linux users there is a Makefile which can be used to compile this example program.

One note: The program drs_exam.cpp published in the previous message needs the current version of the DRS library in DRS.cpp and DRS.h. They are contained in the software release 2.1.1 which has to be downloaded. For simplicity, I attached the two files to this message.

 Hi, Stefan,

drs_exam.cpp is working good to read-out one board.

Now I would like to read-out two boards at the same time using the same trigger( external or internal).

I'm trying to understand and modify the original code for control two board.

Meantime, it would be very appreciated if you give any tips for this.

Thanks,

Heejong

The evaluation boards are not really made for multi-board applications. What you have to do is to maintain an external trigger which synchronizes the boards. So you need:

- two boards connected to two USB ports

- an external flip-flop connected to the two trigger inputs of both boards

If a trigger is sent to the flip-flop, it sends a trigger to both evaluation boards. You poll on one of the boards to see if it has triggered (vis IsBusy()), then you read out both boards. Now you have to reset the external flip-flop somehow from the computer. If you have a CAMAC I/O board or some other means of sending a logical signal to it, that could do the job. From the software point, you get a "DRS" object upon initialization, which contains then two "DRSBoard" objects, over which you can iterate. Look at the "drscl" program from the distribution on how to do that.

Hi, Stefan,

I found that my collaborator bought 2 older version of evaluation board before.
They are the version 1.2 in plastics case with firmware 13191.

Can I upgrade the firmware from 13191 to 13279?
I'm wondering if the older version of evaluation board is working with firmware 13279.

Thanks,
Heejong

Hi, Stefan,

I found that my collaborator bought 2 older version of evaluation board before.
They are the version 1.2 in plastics case with firmware 13191.

Can I upgrade the firmware from 13191 to 13279?
I'm wondering if the older version of evaluation board is working with firmware 13279.

Thanks,
Heejong

I checked and there is no significant difference between the two revisions, so I would just leave it. 

Hi Stefan,

    according to the DRS4 datasheet, if we want an input range centered around U0, the ROFS should be 1.55V-U0. However when I read the codes of the evaluation board application, ROFS seems to be 1.6V-1.25*U0 where the coefficient 1.25 is said to come from sampling cell charge injection correction. Is it the right equation to use? What exactly does that charge injection correction mean?

    Thanks a lot.

1.55V-U0 is the theoretical values, but there are certain "dirt" effects like chip-to-chip variation and charge injection. The difference between various chips is easily 20-30mV, so there is not a single "correct" value. The formula 1.6V-1.25*U0 I developed for a special evaluation board, where it kind of worked better than the theoretical value, but I never made systematic studies. One should average over several chips and use some solid average there. Best is if you try both formulas and check what give you the better linearity.

Hi,

According to DRS4's datasheet, the random noise is 0.35mVrms. Is this the input equivalent noise voltage? It is computed over the 0-950MHz frequency band?

Regards.

You cannot compare the DRS4 noise directly with an amplifier for example. The noise mainly comes from variations of the charge injection into the storage cells, and some noise during the readout process, which happens in a completely different frequency domain than the sampling.

So what I did is to keep the inputs open, measure a 1024-bin waveform, and compute the RMS of this waveform. So I believe that this is kind of equivalent noise voltage from 1-950 MHz. It does not start from zero since very low frequency noise (like 50 Hz) just causes a baseline shift and does not influence the RMS, but this is not so important since in most applications people do an event-by-event baseline subtraction to get rid of low frequency noise in their apparatus. The 0.35 mV RMS also depend on the electronics around the chip. On our USB evaluation board the noise it typically smaller (0.31 mV RMS), while in some VME board we measure 0.42 mV RMS. If you do the perfect analog design around the chip, you can maybe push this maybe even lower.

Hi all,

i'm an electronics engineering student at UCM (Madrid) working on my master's thesis within the CTA collaboration. I'm designing the readout electronics for the telescope's camera, and i'm focusing in using GAPDs instead of PMTs and using the domino chip for the sampling of the signal. I was wondering if there is a spice and/or RF model of the DRS4 chip available. It would be very useful to perform some simulations before deciding to use the chip as the sampling solution for our prototypes.

If the answer is negative, can you give me some advise for modelling the chip in spice? Have you done any simulations?

Thanks in advance,

Ignacio Diéguez Estremera.

Yes there is a transistor-level spice model, which I used to design the chip, but you won't be happy with it: Given the 500,000+ transistors on the chip, a 100 ns simulation takes a couple of weeks. We tried to make a simplified model just for the analog input using some measured S-parameters, but found that the RF behavior of the chip is almost impossible to describe to better than let's say 50%. In the end you have to fine-tune your analog front-end experimentally, to obtain optimal bandwidth. We are just working on a reference design with gives you 850 MHz bandwidth using an active input buffer.

 Thanks for the information.

I would like to try the huge :-) model. Can you send it to my email address? Since the input signal are pulses of a few nanoseconds at FHWM, the simulation time may be reduced. I will post some feedback in the forum once i give it a try.

Kind regards.

I just checked and realized that we are not allowed to give out the "huge" model since it contains parameters from the chip manufacturer's library which are confidentially. 

 Thank you for the effort anyway.

So i guess i won't be able to include drs4 in my simulations :-(. Any other suggestions? Maybe the S-params model you where working on? Anything is better than nothing :-)

Please find attached the S-parameters. 

 Thanks :-)

 Hi, we plan to do a time interpolating among the eight channels on a single chip to obtain a maximum 40 GSPS (or, maybe 30 GSPS ) sampling rate.  Hence RF behavior of the anlog input is very important for us.

Will you give us some advice on the modeling of  the anlog input circuit of the chip?  Perhaps just the Spice model of the analog input?

The attached S parameters I found  here is for f_s =1 GSPS, what about fs=5GSPS?

thanks in advance,

                                                                               Jinhong Wang (wangjinh@mail.ustc.edu.cn  ;  alleyor.wang@gmail.com)

To be honest, we never really succeeded to do any good simulation above let's say 500 MHz. We carefully tried to simulate the bond wire of the chip, the parasitic capacitances of the traces of the chip etc. but we always were off by a factor or two or so. Other groups reported the same problems. Some even did some 3D simulation model, without success. So our conclusion is that if you are interested in anything precise above 500 MHz, do a measurement.

So our current best design is with the THS4508. There is an AC coupled version going to 600 MHz, and a DC coupled version (uses more power) going to 800 MHz (-3dB). If you use passive inputs with a transformer for example, you can't go above 220 MHz. Next week I will publish both designs in this forum.

Hi Stefan,

    I read in the DRS datasheet that the bandwidth for the transparent mode OUT+ is only 200MHz which I think cannot be improved by any active input buffer; so if you want to operate the chip for really high frequency input, would it be better to feed on-board discriminators not from the output of DRS but from the input end?

    Thanks!

First, the 200 MHz is not correct. Table 1 clearly states ANALOG OUTPUTS - Bandwidth (-3dB): 50 MHz. This is also shown in plot 11 (revision 0.9). But that does not necessarily mean that you have to drive your discriminators from the input of the DRS4 chip. If you use this for triggering, a 1-2 ns timing jitter does not matter, since stopping the domino wave anyhow has a 3-4 cell jitter. If you send a very fast signal though a 50 MHz low pass filter, the timing anyhow doe not change, only the slope of your signal gets lower, so you are more sensitive to noise, which in turn causes the 1-2 ns timing jitter. But I personally would not worry about that too much. Putting any signal splitting components in the input path would reduce the input bandwidth, which would be much more of an issue.

Hi Stefan,

    on our board some DRS chips draw a lot of current through DVDD after power-up and heat up significantly--it is true that our board doesn't have weak pull-down resistors at DENABLE and DWRITE output pins of FPGA, so this problem might have been caused by that, but a reinitialization of the Domino circuit doesn't help either. We tried different capacitors at DVDD and it seemed the larger the capacitance, the better the result--with a capacitor larger than 10nF some of the DRS chips could work happily in the normal way while if the capacitor is only 4.7nF all of them got very hot. Would you please provide some suggestions why there should be such a problem?

    Thanks a lot!

I found that sometimes even a reinitialization fails if the pull-down resistors are missing. So instead playing with capacitors at DVDD, I would just solder two resistors on the board which should fix the problem completely.

 Thanks! After adding pull-down resistors the voltages come back to normal.

However there is another weird problem that arises: a reset pulse seems unable to set the internal shift registers to default values. For example, after reset without addressing the Config Register the PLL will not try to lock with external reference clock. Even if I explicitly address the Config Register after reset and have the PLL locked, some channels of the chip will give null output during readout while other channels work normally. Could it be that some channels are not initiated properly with the Domino circuit?

Something is wrong. I have 800 chips, and they all start up fine. Check with your scope the RESET, DSPEED, DENABLE and DTAP signals. When RESET is applied, DSPEED should go to 2.5 V. When DENABLE goes high, the domino wave is started and you should see DTAP toggle. DSPEED is then lowered by the PLL until DTAP matches your external reference clock. I usually keep DENABLE high all the time after initialization, so the domino wave just continues running.

Another problem could however be the chip readout. If some channel gives null output, it could be that your readout has a problem. Do you use RSRLOAD to initialize the readout sequence?

 Yes; I used RSRLOAD to trigger readout of all channels in parallel so the asymmetry between channels of the same chip is really a big puzzle. Also during reset DSPEED indeed goes to 2.5V, but after reset the PLL will not try to lock with the external reference clock and lower DSPEED. Instead the Domino circuit just oscillates at the highest frequency by itself.

A more confusing discovery is that the SRIN level before starting the Domino wave could affect the behavior of the PLL. I mean the level of SRIN when the chip is at A="1111" or "1010". Is SRIN supposed to influence the chip even in these standby or transparent modes?

Just some ideas:

• Is DENABLE really kept high all the time?
• Is DRESET only applied once during initialization, after that it should stay high
• Does  REFCLK+/REFCLK- really toggle at the required sampling speed / 2048?
• Is the REFCLK really a good differential signal? Note that it must be biased properly since the DRS4 inputs are high impedance
• Is the Bit1 in the Config Register really at "1" to enable the PLL?

The only way the SRIN level could affect the PLL is if you address the Config Register (A="1100") and you clock in a few bits with SRCLK.

Have you thought about 'crazy' things such as:

• Defining the DRS4 chip wronly in your CAD software so that the pins are different from what you think?
• Some soldering problem of the DRS4 chips (we had this in the past) so that some pins are not connected at all and others have shorts

I guess you checked most of the things, so I'm just wildly guessing in order to stimulate some thoughts.

The ultimate check would be to get one of the evaluation boards (I sent a few to Jean-Francois Genat some time ago...) and compare the DRS4 signals pin by pin.

 Hi Stefan

       I designed the evaluation board for our experiment. On our boards, I  encountered the similar problem when working on the PLL of DRS4. I compared the following two configuration process, which on with PLL locked, the other not,

   Process1: 

       step 1: Set DEnable and DWrite low, 

      Step2 : Reset DRS4 with a negative pulse of about 900 ns

      Step3: Set DEnable high,  thus do nothing but wait

       I found DRS4 PLL working and locked. 

  Process 2:

   Step 1: Set DEnable and DWrite low, 

  Step2 : Reset DRS4 with a negative pulse of about 900 ns 

  Step3: Set Config. Register( "11111111" .of course, this step was not necessary, just to see whether SPI was working properly from DTAP when set to "11111110")

  Step4: Set The read shift Register ( full read out mode)

  Step5: Set DEnable high, 

  Step6: Set DWrite high  , thus low it , and prepare to read the waveform.

  Well, I found in this case, the PLL was not locked, I am sure there was no problem with my SPI configuration process of DRS4. 

  toggle from DTAP could be viewed, but not stable. 

 Any Suggestions ?

  thanks.

So the main difference, if I understand correctly, is the setting of the Config Register. Actually I never tried that, I always went with the default settings (all "1"). What happens if you write "00000000"? You know Bit1 controls the PLL, maybe there is a bug and the signal needs to be inverted. 

 Hi, Stefan,

       The problem was fixed by setting Reg_addr "1001" instead of "1111" when in idle state, I was confused. 

 Hi Stefan, 

      I found DRS draw a lot of current when applied Reset after power on,  and the PLL does not work properly. I believe there was something that I misunderstood. So,  what will happen when Reset is applied more than once after power on? . Though the chip worked well without a Reset,   i want to try to find out what was wrong, for a better understanding of DRS. 

     best regards!

           Jinhong

Have you made sure that DENABLE and DWRITE stays low during the reset? 

 Yes, they are stay low until Reset goes high. the process is as following

   Step1: Reset ='1', DEnable ='0', DWrite ='0', Reg_addr ="1111", Rsload='0', Srin ='0'

  Step2: Reset='0', the others do not change, the low of the pulse is longer than 10 ns.

  Step3: Reset='1', the others do not change, wait for some time

  Step4:  DEnable ='1' to start the domino.

Ok, then I have no idea. I never tried several reset pulses (actually this is not needed), so I have to reproduce the problem myself and investigate it. Actually in all my designs the reset input is just left open, since the internal initial reset is enough, so I have to modify my design first... 

    Ok ,thank you. 

Dear DRS4 users,

a new version of the evaluation board has been designed and is in production now. The main difference is that it uses active input amplifiers, which result in an analog bandwidth of 700 MHz (as compared with the 220 MHz of the previous board) at moderate power consumption, so the board can still be powered by the USB port. New orders will receive boards V3, the old V2 boards are not available any more.

It is mandatory to use the software revision 3.0.0 or later with the new board. This software has also many new features in the oscilloscope application, and together with the new firmware it reduces the noise of the board below 0.5 mV RMS. Although the software can be used with old V2 boards, some limitations might apply due to the old firmware of the boards. People having a Xilinx download cable can flash the firmware contained in the 3.0.0 revision to their V2 board to get all features of the new software.

The evaluation board manual V3 contains the new schematics of the analog inputs using the THS4508 differential amplifier, so people doing their own design can use this schematics as and example.

Best regards,

   Stefan Ritt

 Hi, Stefan, I see in your ppt "Design and performance of 6 GSPS waveform digitizing chip DRS4" , you define DRS4 ENOB as 1Vpp/0.35mv(RMS) = 11.5bit, where, 1Vpp is the linearity input range, and 0.35mv is the rms voltage after offset correction. What I understand is that 0.35mV is obtained from DC offset Correction, hence 11.5 bit is for DC input, am i right?  If true, what about ENOB for AC input in the whole analog bandwidth?  thanks~

The expression ENOB for 1Vpp/0.35mV(RMS) is wrong, but I learned this later. Now I call it SNR. The ENOB is calculated in a more complicated way, see for example http://en.wikipedia.org/wiki/ENOB. If you measure the ENOB without timing correction, it's pretty poor (in the order of 7-8 bits). This is because without timing calibration, a sine input has huge side bands, and the ENOB involves the power of your signal over the power of the side bands. If you do a proper timing calibration, you spectrum gets "sharper", and hence the ENOB increases. But I have to admit that I never measured it carefully, since we are still optimizing the timing calibration. Once we have a perfect timing calibration, I will do it and update the data sheet. 

The design of high frequency differential input stages with the DRS4 is a challenge, since the chip draws quite some current at the input (up to 1 mA at 5 GSPS), which must be sourced by the input buffer. A simple transformer as used in the DRS4 Evaluation Board 2.0 limits the bandwidth to 220 MHz. In meantime two active input stages have been worked out and successfully been tested, both utilizing the THS4508 differential amplifier. The first design is AC-coupled and uses less power, the second design is DC-coupled and uses more power with the benefit of delivering a higher bandwidth.

Both designs use a clamping diode at the input as a protection against high voltage spikes at the input. We used a RCLAMP0502B diode from SEMTECH, but any fast voltage suppressor diode will do the job. 

The CMOFS input to the THS4508 set the common mode of the differential amplifier. In the AC version the level is set to mid-rail (2.5V), in the DC version it's set to 1.8V to match the input range of the DRS4.

The CAL+ and CAL- signals are used to bias the inputs to a well-defined DC level and can also be used to calibrate the chip. For bipolar inputs, they are both set to 0.8V. A positive 0.5V input pulse then drives DRS_IN+ to (0.8+0.25)V = 1.05V and DRS_IN- to (0.8-0.25)V = 0.55V. A negative 0.5V pulse then drives then DRS_IN+ to 0.55V and DRS_IN- to 1.05V. With ROFS=1.6V, the full dynamic range of the DRS4 is then used. Note that the THS4508 has a gain of 2, and the input has a -6dB voltage divider to compensate for that. To use other input ranges, such as -1V...0V, the CAL+ and CAL- signals can be adjusted accordingly. Note that the inputs of the DRS4 must always be between 0.1V and 1.5V.

AC-coupled version

                                                                                                                                                                                                                                     (click to enlarge)

Power supply: +5 V 40 mA

Bandwidth (-3dB): 600 MHz

CMOFS: 2.5 V

Transfer function:

                                                                                                                                                            (click to enlarge)

The transfer function was measured by applying a fixed amplitude sine wave to the input, and measuring the peak-to-peak value of the read out waveform with the DRSOsc application.

DC-coupled Version

The DC-coupled version has a slightly higher power consumption since there is a constant current flowing through the output into the DRS4 chip. On the other hand, the bandwidth is a bit higher and the peaking around 400 MHz is a bit smaller. The input is still AC-coupled, so both positive and negative pulses can be accepted. 

                                                                                                                                                                                                                             (click to enlarge)

Power supply: +5 V 115 mA

Bandwidth (-3dB): 800 MHz

CMOFS: 1.8 V

Transfer function:

                                                                                                                                                              (click to enlarge)

Achievable performance

With the active input stage, much faster rise- and fall times can be achieved. Following picture shows a signal from a external clock having a fall time of about 300 ps being recorded with the AC-coupled version of the active input stage. The fall time of the recorded signal is about 800 ps, which is about the minimum which can be achieved with the AC-coupled version. The DC-coupled version achieves about 700ps.

 Hi, stefan,

No you are right about that. The THS4508 has a gain of +2, and by using the resistor pairs we do

1) Reduce the gain back to unity

2) Reduce the input DC level from 1.8V to 0.9V to match the input range

3) Terminate the signals at the input of the DRS chip to minimize reflections

I know this is not so obvious from the schematic, so thanks for asking.

- Stefan 

 Dear sir,

We have two evaluation boards of DRS4. We would like to use 8 inputs to be recorded on a trigger and we would like to find the relative time difference of inputs. So is it possible to synchronize the sampling frequency of the two evaluation boards. 

with best regards

S S Upadhya

No, not in this version. We plan a future version of the evaluation board with clock synchronization, but that board will not be ready before 2-3 months. Anyhow the board is more meant as an evaluation board, to test the chip and develop own electronics, and not to build a complete DAQ system. Note that CAEN distributes now a VME board containing the four DRS4 chips and 32 channels on a board. 

Well, one thing you can do is to generate an external trigger and send it to the external trigger input of both cards. Then you can determine the time in respect to the trigger point in both boards. But since the trigger cell jitters by 2-3 cells in each chip, the accuracy is limited to about 1-2 ns when running at 2 GS/s. 

 Dear Stefan,

Thanks for the second suggestion. I wanted to do feasibility study of  DRS4 application to our requirement in the experiment 

Thank you again sir,

Upadhya

Dear colleague,

if you live not so far from Zurich, you might be interested in this workshop:

http://www.xtronix.ch/hep/psi_workshop.htm

This is a combined PSI-CAEN presentation of digitizer hardware including the new V1742 board based on the DRS4 chip. The workshop will also show how digital pulse processing can be used to effectively extract time and energy from detector signals, and thus replace more and more traditional analog electronics. Please register at the above site if you are interested.

Best regards,

    Stefan Ritt

I have DSR4 eval board. Found that there are spikes in channels. Procedure Osc::RemoveSpikes to remove them looks litlle dificult. There is simple way, if you doesnt need to measure all 4 channels.Spikes are in all channels, and it looks like they are same in time and value between channels. To remove them, if you are not using one channel, substract that unused channel with spikes from used channel and your data will be without spikes. If you need all 4 inputs, then may be channel 9 could be substracted.

Indeed that's what I had before. If you don't need the 9th channels, you can use it to identify the spikes. But we have applications where we need all 9 channels. That's why I made Osc::RemoveSpikes a bit more complicated, so it will still work when all 9 channels are used. This new version is release 3.1.0. If you just blindly subtract the 9th channel, your noise could increase by a sqrt(2). 

 Hi Stefan, can you give some suggestions on determination of fixed pattern timing jitter of DRS4?  Thanks~

I will prepare some more detailed description of how to do this in the near future, but we are still learning ourselves constantly how to do that better. 

So for the moment I only can recommend you to read the function DRSBoard::CalibrateTiming() and AnalyzeWF(). What you basically do is to define an array of "effective" bin widths t[i]. You start with the nominal bin width (let's say 500ps at 2 GSPS). Now you measure a periodic signal, and look for the zero crossings. If you have a 100 MHz clock, the time between two positive transitions (low-to-high) is 10.000ns. Now you measure the width as seen by the DRS chip, assuming the effective bin widths. The exact zero crossing you interpolate between two samples to improve the accuracy. Now you measure something different, let's say 10.1ns. So you know the ~20 bins between the zero crossings are "too wide", but you don't know which one of them is too wide. So you distribute the "too wide" equally between all bins, that is you decrease the effective width of these bins from 500ps to 500-0.1ns/20=499.995 ps. Then you do this iteratively, that is for all cycles in the waveform, and for many (1000's) of recorded waveforms. It is important that the phase of you measured clock is random, so that all bins are covered equally. Then you realize that the solution oscillates, which you can reduce by using a damping factor (called "damping" in my C code). So you do not correct to 499.995ps, but maybe to 499.999ps. If you iterate often enough, the solution kind of stabilizes.

The attached picture shows the result of such a calibration. Green is the effective bin width which in the end only slightly deviates from 500ps. But the "integral temporal nonlinearity" shows a typical shape for the DRS chip. It's defined as

          n
 Ti[n] = Sum (t[i]-500ps)
         i=0

where t[i] is the effective bin width. So Ti[0] is zero by definition, but the deviation around bin 450 can go up to 1ns at 2 GSPS.

Now you can test you calibration, by measuring again the period of your clock. If you do everything correctly and have a low jitter external clock and no noise on your DRS4 power supply voltages, you should see a residual jitter of about 40ps.

Hope this explanation helps a bit. Let me know if I was not clear enough at some points. 

- Stefan

 Hi, Stefan,

    I noticed other groups of SCA reported the technique to histogram the zero crossings of a sine wave, and use the bin occupancy to derive the effective aperture width.  Recently , I tried this technique to DRS4. In my test, the frequency of the sine wave was selected uncorrelated to the domino frequency.The results were discouraging. Large variations of the domino tap delay was observed.   Besides, I also tried to induce an external trigger, which is uncorrelated to the domino frequency, and histogram the stop positions. Unfortunately, large variations were obtained again. I knew there must be something wrong. Do you have any suggestions?

   The attachment is the histogram of the stop positions (the vertical axis is the bin count, the horizontal axis is the bin number). First, I calculate the ration of each bin count to the total counts, supposed the total count is 10000, count of bin 37 is 12, so the corresponding ratio is 12/10000=0.0012. The bin delay is derived by multiplying its ratio to the whole domino period (1024*1/FSamp, eg., for 5 GSP/s, this period is 200ps *1024). (The bin delay i observed was with an variation of about 30 ps).  If the external trigger is uncorrelated to the domino frequency, so, the stop positions are supposed to distribute equally to all bins? If this is true, can i calculate the bin delay via the histogram ?

   thank you~

                 Wang Jinhong

One obvious problem in your method is your statistics. If you have n hits in a bin of the histogram, the error of n is sqrt(n). So if you measure 100 hits, this is more like 100+-10 hits. If you want a better precision, you need much higher statistics. I myself never used this method, but I attach a typical nonlinearity curve running at 2 GSPS, sot hat you know what you should expect. I do some smoothing between neighbor bins so that they do not scatter too much. As you can see, the integral nonlinearity goes almost up to +-2 ns. This value is smaller at higher sampling speeds.

 - Stefan 

 Thank you, Stefan. It is really kind of you to offer suggestions or comments on our concern. 

Recently, we input a sine wave to our DRS board. DRS works at about 5 GS/s. The frequency varies from 131 MHz to 231MHz. The attached picture shows the reconstructed points of sine wave (vertical is the amplitude, horizontal axis is the point numbers). We noticed that the variation of the length of the zero crossing segments is very large. The max. length is perhaps two times the length of the min. I marked in blue color in the picture.  It means the corresponding sampling interval of the max. is two times of that of the min.  If this is true, DNL of the DRS sampling interval would be very large. We know, for uniform sampling, the length of the zero crossing segments are assumed to be uniform.  Do you have any comments? Thank you~

The length of the segments is a combination of the sampling jitter and the voltage noise. If you signal contains some noise (and all signals do) it will translate to timing jitter. The DNL of the DRS sampling interval shows a variation from the mean of typically 30%. After you correct for it, it will of course become much smaller. As I said, some people measured 10 ps timing with the DRS4 after careful timing calibration. 

Hello,

I am designing a DAQ board with both DRS4 + AD9222 and a  FPGA to monitor.

Do I have to change the default value of O-OFS ?

Does a simple low-pass filter (series resistor + capacitor) on each AD9222 input is enough to limit the noise ?

I am planning to use the (DRS4,AD9222,FPGA) group as both a trigger and digitizing system (as shown in the DRS4 datasheet). The DRS4 will be working at 5Ghz with 8 active channels.
So each channel will have a time depth of 1/5Ghz x 1024 = 204.8ns. So, in order to miss nothing, the ADC latency + the trigger decision must be inferior to 204.8ns, am I correct ?
This leads me to implement on my board the 65Mhz version of the AD9222 as this converter has a 8 clock period latency, i.e. 123ns and it left me 81ns to perform a trigger decision ?

Cordially,

G.Blanchard

I'm not so sure about the temperature stability of the default (DRS4 internal O-OFS) value, that's why I used a precision DAC in my design. But actually I never tried without. Probably the default internal value is good enough if you calibrate each chip (which you do anyhow).

Most designs use no filter between DRS4 and AD9222. Since the DRS4 output is BW limited at around 50 MHz, there is not much you win if you put a 32.5 MHz low pass there. And the PCS gets just so much simpler.

You are right with the latency of the AD9222, this is an issue. From the remaining 81 ns you loose a few going out of the FPGA, you need one or two FPGA clock cycles to make the decision, the DRS4 has also some stopping latency (maybe 10 ns). So you are at the edge. Some people use hardware comparators which are faster than the AD9222, one guy uses even directly an LVDS input of the FPGA "mis-used" as a comparator, where the comparator level (=LVDS negative input) comes from a DAC.

- Stefan

 Like Stefan pointed out, your time constraints are quite tight. In those 81 ns, you also need to deserialize the AD9222 output. Unless you implement some really fancy input comparison logic, this will consume another 1-2 ADC clock cycles. Perhaps you should first verify that your FPGA design actually can do its job within those 81 ns. In our system, we sample at only 1-2 GHz and have enough margin to implement really complex triggers in FPGA. But the total latency (ADC + FPGA deserialization) takes 250 ns.

Depending on the application, you do need a low-pass filter. Not only because of the noise, but also in order to be able to trigger reliably. Using fast PMTs for example, you will not be able to see all pulses in full size if the bandwidth is 50 MHz and you're only sampling at 65 MSPS.

Hannes

Thank you for your answers,

Another question : Have you ever tried to split the differential signal at the output of the DRS4 chip ? For example to feed both an AD9222 and a diff. amplifier (followed by discriminators) ?

Yes. Just have a look at the schematics of the evaluation board. This is exactly what is done there.

Actually in the newest version we went one step further and put the comparator at the input of the DRS chip. This way it is active even during the readout of the DRS4 chip and we can use this as a counter to count the overall hit rate at the input.

- Stefan

Hi Stefan,

When I compiled DRS4 software version 4.0.0 on Linux (Debian Squeeze) I got this compilation error:

g++ -g -O2 -Wall -Wuninitialized -fno-strict-aliasing -Iinclude -DOS_LINUX -DHAVE_LIBUSB -DUSE_DRS_MUTEX musbstd.o mxml.o strlcpy.o DRS.o ConfigDialog.o DOFrame.o DOScreen.o DRSOsc.o MeasureDialog.o Measurement.o Osci.o InfoDialog.o DisplayDialog.o AboutDialog.o EPThread.o rb.o main.o -o drsosc -lpthread -lutil -lusb -pthread   -lwx_gtk2u_richtext-2.8 -lwx_gtk2u_aui-2.8 -lwx_gtk2u_xrc-2.8 -lwx_gtk2u_qa-2.8 -lwx_gtk2u_html-2.8 -lwx_gtk2u_adv-2.8 -lwx_gtk2u_core-2.8 -lwx_baseu_xml-2.8 -lwx_baseu_net-2.8 -lwx_baseu-2.8
DOFrame.o: In function `DOFrame':
/srv/zatserkl/work/drs4/drs-4.0.0/src/DOFrame.cpp:237: undefined reference to `TriggerDialog::TriggerDialog(wxWindow*)'
/srv/zatserkl/work/drs4/drs-4.0.0/src/DOFrame.cpp:237: undefined reference to `TriggerDialog::TriggerDialog(wxWindow*)'
collect2: ld returned 1 exit status
make: *** [drsosc] Error 1

To fix it I added TriggerDialog.o into CPP_OBJ line of the Makefile:

CPP_OBJ       = DRS.o ConfigDialog.o DOFrame.o DOScreen.o DRSOsc.o MeasureDialog.o Measurement.o Osci.o InfoDialog.o DisplayDialog.o AboutDialog.o EPThread.o rb.o TriggerDialog.o

Best,

Andriy.

Thanks. I added your fix to the current 4.0.0 distribution.

- Stefan 

Hi,

Our setup uses a DRS4 evaluation board (version 2.0).

Although we trigger the board at a rate of ~4kHz (on channel2), readout through USB2 is only happening at a rate of ~125Hz.

After some investigation, we could pin down that it is due to the time it takes to complete the following commands: musb_write() and musb_read() which both take ~150 microsecond to complete. Because they are called multiple times, reading out 1 trigger takes ~8 millisecond which explains the 125Hz we're seeing.

Is ~150 us to complete a musb_read()/musb_write() command expected?

Is there any way we could speed up the readout rate of the DRS4 board so that data acquisition through USB2 is closer to our trigger rate of 4kHz?

Any feedback you might have on this topic would be greatly appreciated.

Many thanks,

Aurelien

With version 4 of the DRSOsc program and a decent computer, you should be able to achieve something close to 500 Hz, but that's the limit. The board is for evaluation purposes of the chip, not for production data acquisition. The main limit comes from USB2, which is limited to ~25 MB/sec. We are in the process of designing a new board with Gigabit Ethernet readout, with which you should be able to get your 4 kHz. But this board will not be ready before spring. There is also a VME board by CAEN in Italy which sits in a VME crate. This board is also much faster than the USB board. Here is the link:

http://www.caen.it/csite/CaenProfList.jsp?parent=13&Type=WOCateg&prodsupp=home

Dear Dr. Ritt,

    In the DRS 4 datasheet it is recommended to sample the analog output of the chip after 8~10 ns of the SRCLK edge for it to stablize and thus a phase shift between SRCLK and the ADC sampling clock is necessary. However in the latest version of the evaluation board firmware the phase-shifted clock was generated but not really used for the ADC interface. Is there any reason for that?

Good questions. I looked myself in the code and found:

  drs_readout_clk       <= I_CLK33;

  drs_readout_clk_ps    <= I_CLK33; -- phase shifted clock for FADC

  drs_serial_clk        <= I_CLK33;

which is apparently wrong (should be drs_readout_clk_ps <= I_CLK33_PS;) . But apparently the board is working with the unshifted clock. Could be that the PCB traces to the DRS and the ADC have different lengths, and by accident, they have just the right value.

The way to find that out is to keep the ADC clock phase variable (most FPGAs allow a +-5 ns phase adjustment inside their clock blocks), and then try different values. If the phase shift is wrong, you will see spikes every 32 samples in the readout. The spikes are always there (from some internal switching of bus segments), and you can see them with a differential probe at the DRS output. The ADC phase must then be made such that the sampling point of the ADC comes after that spike, just at the end of the settling time, barely before the next analog value shows up at the DRS output. This is a bit tricky and can be made best just by trying out different values.

I want to measure the signal from PMT . But it is a current signal, should i just put a series resistance, or use a amplifier to convert it to voltage signal before drs4?  

Can you give me some advice ? 

The evaluation board has a 50 Ohm termination resistor, which already converts your current into a voltage signal. If the resulting signal is too low (<20 mV) you can put in an amplifier or raise the HV of your PMT (inside the valid range given by its datasheet of course).

- Stefan 

Hello,

I was just building version 3.1.0 and ran into some problems in DOScreen.cpp.  Basically the conversions from
char* to wxString were generating "ambiguous overload" errors (in gcc 4.4.3, wx-2.8)

The simple fix is given in  the following diff output.

Cheers,

Bob

diff drs-3.1.0_o/src/DOScreen.cpp drs-3.1.0/src
237c237
<      wxst = wxString(m_frame->GetOsci()->GetDebugMsg(),wxConvUTF8);  //BH
---
>       wxst = m_frame->GetOsci()->GetDebugMsg();
246c246
<       wxst = wxString(m_debugMsg,wxConvUTF8);  //BH
---
>       wxst = m_debugMsg;
477c477
<     wxst = wxString("AUTO",wxConvUTF8); //BH
---
>          wxst = "AUTO";
479c479
<     wxst = wxString("TRIG?",wxConvUTF8);  //BH
---
>          wxst = "TRIG?";
 

> Hello,
> 
> I was just building version 3.1.0 and ran into some problems in DOScreen.cpp.  Basically the conversions from
> char* to wxString were generating "ambiguous overload" errors (in gcc 4.4.3, wx-2.8)
> 
> The simple fix is given in  the following diff output.
> 
> Cheers,
> 
> Bob
> 
> diff drs-3.1.0_o/src/DOScreen.cpp drs-3.1.0/src
> 237c237
> <      wxst = wxString(m_frame->GetOsci()->GetDebugMsg(),wxConvUTF8);  //BH
> ---
> >       wxst = m_frame->GetOsci()->GetDebugMsg();
> 246c246
> <       wxst = wxString(m_debugMsg,wxConvUTF8);  //BH
> ---
> >       wxst = m_debugMsg;
> 477c477
> <     wxst = wxString("AUTO",wxConvUTF8); //BH
> ---
> >          wxst = "AUTO";
> 479c479
> <     wxst = wxString("TRIG?",wxConvUTF8);  //BH
> ---
> >          wxst = "TRIG?";
>  

Thanks for mentioning this. I always overlook this because I develop under Windows where this warning does not show 
up. I fixed that in the current version. Usually I just use _T() instead wxString() because this is shorter and 
recommended by the developers.

Cheers, Stefan.

> I was just building version 3.1.0 and ran into some problems in DOScreen.cpp.  Basically the conversions from
> char* to wxString were generating "ambiguous overload" errors (in gcc 4.4.3, wx-2.8)
> 
> The simple fix is given in  the following diff output.

Today, I ran into the same problem and was happy to find your fix. I've incorporated it into a unified diff file,
that can easily be applied with the patch program by saving it into a file ('drsosc-3.1.0-wxfix.patch', say), and
in the drs-3.1.0 directory running:

patch -1 < drsosc-3.1.0-wxfix.patch

This is the file:

--- src/DOScreen.cpp.orig	2011-12-09 15:49:48.682201902 +0100
+++ src/DOScreen.cpp		2011-12-09 15:51:45.666000111 +0100
@@ -234,7 +234,7 @@ void DOScreen::DrawWaveform(wxDC& dc, wx
 
    // display optional debug messages
    if (*m_frame->GetOsci()->GetDebugMsg()) {
-      wxst = m_frame->GetOsci()->GetDebugMsg();
+      wxst = wxString(m_frame->GetOsci()->GetDebugMsg(),wxConvUTF8);
       dc.SetPen(wxPen(*wxLIGHT_GREY, 1, wxSOLID));
       dc.SetBrush(*wxGREEN);
       dc.SetTextForeground(*wxBLACK);
@@ -243,7 +243,7 @@ void DOScreen::DrawWaveform(wxDC& dc, wx
       dc.DrawText(wxst, m_x1+4, m_y1+2);
    }
    if (m_debugMsg[0]) {
-      wxst = m_debugMsg;
+      wxst = wxString(m_debugMsg,wxConvUTF8);
       dc.SetPen(wxPen(*wxLIGHT_GREY, 1, wxSOLID));
       dc.SetBrush(*wxGREEN);
       dc.SetTextForeground(*wxBLACK);
@@ -474,9 +474,9 @@ void DOScreen::DrawWaveform(wxDC& dc, wx
    if (m_osci->GetNumberOfBoards() && m_osci->IsIdle()) {
       dc.SetTextForeground(*wxGREEN);
       if (m_osci->GetTriggerMode() == TM_AUTO)
-         wxst = "AUTO";
+         wxst = wxString("AUTO",wxConvUTF8);
       else
-         wxst = "TRIG?";
+         wxst = wxString("TRIG?",wxConvUTF8);
       dc.GetTextExtent(wxst, &w, &h);
       dc.DrawText(wxst, m_x2 - w - 2, m_y1 + 1);
    }

In the attachement you will find a working DC-coupled input stage to the DRS4 chip. The bandwidth of this design is about 700 MHz, the gain is 1.

The upper version does not have an additional input buffer. This is not a very "clean" design, since the differential driver has an input impedance of 150 Ohm, which together with the 75 Ohm termination resistor gives about 50 Ohm termination. 

The lover version has an additional input buffer, which nicely decouples the input from the differential driver, so a proper 50 Ohm termination can be used at the cost of additional power for that buffer.

The COM common mode voltage and the OFS voltage have to be set according to the required input range, so that ranges such as 0V...1V, -0.5V...+0.5V, -1V...0V can be used. The COM voltage can be high impedance (simple resistor divider), while the OFS voltage needs to be low impedance (fast active buffer). The analog switch ADG918 can be used to digitize a precise calibration voltage CAL+, which can then be used for precise gain calibration of the DRS4 sampling cells.

Hi Stefan,

    I have a question regarding the DRS 4 evaluation board firmware for the 8051 controller embedded in the CY7C68013 USB chip: on the board the controller is running at 12 MHz and the FIFO interface of the USB chip is running at 30 MHz, so the number of delay cycles for synchronization as defined in fx2sdly.h should be (3*12000+5*30000-1)/(2*30000)=3, but the actual number used in drs_eval.c is (3*12000+5*48000-1)/(2*48000)=2, so there is a mismatch between the IFCLK frequency used in this calculation and the actual IFCLK frequency configured. Am I misunderstanding something or is there an explanation for that?

    Thanks,

Hao Huan

You are right. The SYNCDELAY should contain three wait cycles. I kind of remember that this delay is not very critical. That might be the reason why the system works even with the wrong delay reliably. 

Hello,

I'm using DRS4 evaluation board version4 in Linux (Scientific Linux 5).

Version4 software (drs-4.0.0) was installed without any troubles.

The oscilloscope interfrace program (drsosc) is working fine with version4 software.

But when I tried drs_exam program, it doesn't work as expected.

(500 mV positive (width 50ns)  pulse is connected to Ch#1).

It keeps waiting trigger in the first event.

In the previous version (board/software drs-3.0.0), drs_exam program worked well.

I'm wondering if anybody is using drs_exam with V4 evaluation board.

Any comments/help would be welcomed.

Thanks,

Heejong

The issue is that the V4 board has new trigger capabilities (such as coincidences between two channels) which require a slightly different configuration. Here it the new code:

   /* use following lines to enable hardware trigger on CH1 at 50 mV positive edge */
   if (b->GetBoardType() == 8) {     // Evaluaiton Board V4
      b->EnableTrigger(1, 0);           // enable hardware trigger
      b->SetTriggerSource(1<<0);        // set CH1 as source
   } else {                          // Evaluation Board V3
      b->EnableTrigger(0, 1);           // lemo off, analog trigger on
      b->SetTriggerSource(0);           // use CH1 as source
   }

The complete file is attached. Please try again with the new code. Probably next week I will make a new software release (including a Mac version of all programs) which will contain the new code. Sorry for any inconvenience.

Best regards,
Stefan

Hello Stefan,

Thanks for your prompt reply.

drs_exam is working now after modification as above.

By some trials, I found that external trigger is possible by 'b->EnableTrigger(1,0); b->SetTriggerSource(1<<4);'

Best,

Heejong

Hello,

We are using DRS4 Rev.2.0 board.

We want to measure number of pulses generated  by charge particle detector. These negative going analog pulses are very fast having rise time about 2nS.

We want keep threshold level to -20mV. We expected pulse rate to be about 100 to 200 Hz.

I need help to implement this in  current DRS board with  dead time free operation.

If you just want to count pulses, you do not need a DRS board. Just use a discriminator and a counter, that's much simpler. The DRS board is not dead time free. 

 Thanks for your prompt reply.

Along with pulse rate  we also want see pulse shape as well as charge measurements. That is why we are exploring this option with our existing DRS Set-up.

I understand that. But still the board has some dead time which is dominated by the USB data transfer speed.

There is a way to perform the counting dead time free, but that requires the V4 board, which has a hardware comparator on all four channels (The V2 board has only one comparator and a multiplexer). The output of these comparators go directly to the FPGA, which can then trigger on these signals. In principle one could implement a hardware counter in the FPGA, which works practically dead time free. But this requires a new firmware which has to be written. Either you do it yourself using the Xilinx development tools, or you wait until I find some time to implement this, which could take a couple of weeks or even months.

Best regards,

Stefan 

 Thank you very much.

With regards,

Ravindra R. Shinde

Hello,

I'm co-organizing the upcoming Real Time Conference, which covers also fields of waveform processing and sampling, so it might be interesting for people working with the DRS4 chip. If you have recent results, you could also consider to send an abstract to this conference.  It will be nicely located in Berkeley, California. We plan excursions to San Francisco and to Napa Valley.

Best regards,

Stefan Ritt

18th Real Time Conference
June 11 – 15, 2012
Berkeley, CA

We invite you to the Hotel Shattuck Plaza in downtown Berkeley, California for
the 2012 Real-Time Conference (RT2012).   It will take place Monday, June 11
through Friday, June 15, 2012, with optional pre-conference tutorials Saturday
and Sunday, June 9-10.

Like the previous editions, RT2012 will be a multidisciplinary conference
devoted to the latest developments on realtime techniques in the fields of
plasma and nuclear fusion, particle physics, nuclear physics and astrophysics,
space science, accelerators, medical physics, nuclear power instrumentation and
other radiation instrumentation.

Abstract submission is open as of 18 January (deadline 2 March). Please visit

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abstract.

Call for Abstracts 

RT 2012 is an interdisciplinary conference on realtime data acquisition and
computing applications in the physical sciences. These applications include:

* High energy physics 
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* General Radiation Instrumentation 

Specific topics include (but are certainly not limited to) the list shown below.
We welcome correspondence to see how your research fits our venue.   

Key Dates

* Abstract submission opened:  January 18, 2012 
* Abstract deadline:  March 2, 2012 
* Program available: April 2 

Suggested Topics

* Realtime system architectures 
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Contact Information

If you have a question or wish to opt in for occasional e-mail updates about
RT2012, send us a message at RT2012@lbl.gov. To view full conference
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Hello.

We are designing a waveform sampling board for Si strip array detector ,whose rise time is less than 10 ns, which makes we doubt whether the DRS4 can do more accurate than traditional charge integral circuit for charge measuring.

So we need to know what sort of detectors for physical experiment the DRS4 has been used in?

Can you give me some information? For example, Si strip array detector or CsI scintillator r ball detector ? PMT or APD ?

DRS4 is used for PMTs and APDs. The minimal rise/fall time which can be recorded with the DRS4 on the evaluation boards is about 0.8ns (see elog:84). Concerning charge measurement, it depends on your integration time. If your signal is for example 20ns and you sample with 5 GSPS, you get actually 100 samples. You digitize with 12 bits, but the S/N ratio is more like 11.5 bits. But since you have 100 samples, the accuracy of the measurement scales with sqrt(100)=10. So you have more like 11.5+3 bits = 14-15 bits, or a SNR of 20'000. Now your signal usually does not have an amplitude of 1V, will be more like 100mV or so, in which case your SNR goes to 2000. But this still gives you a resolution of 1/2000 = 0.5 per mille.

We did tests with a Ge detector for spectroscopy applications, where we used a shaping time of 2 micro seconds, both with traditional electronics and the DRS4, integrating the signal over 2 micro seconds. Both gave a resolution of about 0.4%, indicating that the resolution was not limited by the DRS but by the detector.

Best regards,

Stefan 

Quick question - what type of connectors are used for the trigger and clock in/out on the v4 eval board?

Hello,

I am writing a VHDL code to drive a DRS4 chip.

In order to configure the DRS4 chip, I have to set the "Config Register" and the "Write Shift Register" then ... (I do not plan to use simultaneous WR and R so I guess the Write Config Reg. is not needed)

My question is :

When do we have to perform a "Read Shift Register Initialization" ?

Every time before a full read-out, or juste once after a DRS4 reset ?

Further more, is this initialization needed for the ROI mode ?

And at last do the level of the DENABLE and DWRITE signals matter for the "Read Shift Register Initialization" ?

(To sum up : what is the purpose of the Read Shift Register and how does it work ?)

Cordially,

G.Blanchard.

There are two readout modes "Full Readout Mode" and  "ROI mode". 

In the Full Readout Mode, the Read Shift Register has to be initialized before the first readout by applying the sequence shown in Figure 11 in the data sheet. This clears the full shift register and sets the first cell to "1". In principle in the following events one applies each time 1024 clocks. Since the shift register is circula, the single "1" rotates through the shift register and is at the same position after 1024 clocks. So in principle the register does not have to be re-initialized. To be hones I have never tried this myself, so I'm not completely sure if that works.

In the ROI mode, you initialize the Read Shift Register by a single RSRLOAD pulse as shown in Figure 15. Since the inverter chain stops at different positions in each event, this pulse has to be applied before each event. The SROUT bits will then tell you where the inverter chain has been stopped.

Most people I know of use the ROI mode, since the initialization is much simpler (just a single pulse).

Best regards,

Stefan

 I have two BaF2 detectors with PMT connected to Ch1 and Ch2. At this time Im using external triger module to start DRS4. My evalution board is version 3 so I have no possibility to trigger on two or more pulses occurence on different channels. But I have this idea, trigger with analog trigger on channel 1 (start detector) will start measurement on all channels. After that using FPGA inside EVM to look if some value in Ch2 is bigger as treshold value for example 0,5V and if yes then send data by USB to PC, if signal in Ch2 is lower then restart measurement and wait on triger in Ch1. This way I want to eliminate false data transfer throw USB. Is this possible to implement it into DRS4 evaluation board firmware ?

Thanks.

It is muuuuch easier to upgrade to a V4 board!

Modification of firmware is not so easy. You have to learn and understand VHDL. Then, you have to add additional registers for this thresholds, which requires modification of the C library as well. The data inside the evaluation boards is not yet calibrated (this is only done on the C library), so you have an uncertainty of 30-40mV in this data. 

Ok, except this, I would have a question regarding to the new trigering posibility in V4 board. At this time, I am using Ztec ZT4612 which has some pattern triger posibility. Output from this card is used as an external trigger. Regarding this I have found a problem. Pulses from PMT have about 5-8 ns width. But I need to measure time diferences between pulses in range from 0-50ns. Problem is, that coincidence between pulses is working only on short pulse area (5-8ns) when they are overlapped. Additionaly the result histogram of time diferences is proportional to the pulse shapes. I solve this problem enabling 20MHz LPF filter in ZT4612, so the pulses are wider and overlaped on larger area. But, how it is with the V4 board? Will it trigger if I have for example one 5ns pulse on begiinning of CH1 and second pulse for example 50 ns later on Ch2 with the same probability when pulses are in the same time position?

No. 

Hello. I need to digitize pulses from two PMT. After pulse on first PMT I have to save all pulses from second PMT in range 200 ns (and starting pulse from the first, and time range between pulse from 1st PMT and pulses from 2nd PMT). Is it possible with DRS evaluation board?

If you run at 2 GSPS, you have a time window of 500 ns like on an oscilloscope. If you trigger on 1st PMT, you will get the traces of all 4 inputs for the next 500 ns. So I guess this is what you want. 

 Ok. And, If I understand correctly, the main bottleneck in data readout is USB. I.e., theoretically maximum readout rate is 500 Hz. Is it true?

On the evaluation board, yes. This board is not optimized for high readout rate. If you do your own electronics, like GBit Ethernet, you could be much faster. 

 What is the readout rate via GBit Ethernet that you have achieved?

Where is the bottleneck in ethernet?

What is the proposed scheme by which the GBit Ethernet will be implemented, will the DRS4 Eval Board have to wait for the computer to respond before sending the data (wouldn't this make the readout much slower?), or will the DRS4 Eval Board keep sending the data to the computer?

With GBit Ethernet you get close to 100 MB/sec, which is the maximal line speed. The protocol to be implemented will achieve that rate. What one usually does is to send events in large blocks upon request from the PC. The trick is to do the request in a clever way, like using a high water mark on the receiving event buffer. So as long as the PC can digest the data quickly enough, the board just keeps sending, which means no overhead.

Hello again. I have not got evaluation board yet, but already faced some difficulties:) I'm trying to compile drs_exam.cpp on Windows 7 using dev-c++ with imagelib-2 and WxWindows 2.4.2 DevPaks installed, but nothing works. Compile log is attached. Honestly, I'm not very familiar with c++, so any suggestions will be helpful. Thank you.

I have no experience with dev-c++, so I cannot be of help here. The supported systems are Linux and Windows with MS Visual C++. But it looks like the problems are related to compiling wxWidgets, which actually you do NOT need for drs_exam.cpp. The wxWidgets library is only needed for the DRSOsc application. If you want to compile it anyhow, first learn how to compile standard WxWidgets applications from

http://www.wxwidgets.org/docs/tutorials/devcpp.htm

Best regards,

Stefan 

Ok, this was my bad, I added some unnecessary files to project. Drs_exam compiles well with ms vc++. Thanks!

 Hi,

we are planning to use the DRS4 in our board for 1 GHz sampling and digitization.

I have seen in the data sheet that "For the PLL to work, an external loop filter is required. This filter ensures quick locking and stable operation at the desired sampling frequency".

What formula do you use to calculate the values of R, C1 and C2?

Can we use the same given value for different frequencies?

Thanks,

Mayak

I never worked out an exact formula for the parameters. It also depends if you want a fast locking time, or a low phase jitter of the PLL. A good starting point are the values from the evaluation board:

R = 130 Ohm

C1 = 4.7 nF

C2 = 1 uF

They should work from 800 MHz to 5 GHz.

- Stefan 

Hi,

I found an old thread regarding a fix for DOScreen.cpp for DRS-3.1.0, that fixes an "ambiguous overload problem." Currently when I attempt to build the drs-4.0.0, I get this similar error:

src/DOScreen.cpp:332:39: error: call of overloaded ‘Append(int)’ is ambiguous
 

This section of code is different than what the previous thread was correcting, and though I attempted to apply the logic of the old thread, I haven't fixed this yet.

The following is the code for that section:

-----

329  for (int i=0 ; i<5 ; i++)
330       if (tc & (1<<(i+8))) {
331            if (i < 4)
332              wxst1.Append(wxT('1'+i));
333            else
334              wxst1.Append(wxT('E'));
335           wxst1.Append(wxT('&'));
336        }
337      if (wxst1.Length() > 0)
338         wxst1 = wxst1.Left(wxst1.Length()-1);
339      wxst1.Append(wxT(')'));

------

I've attempted a few fixes, but unfortunately, my understanding of the code is not great, and I haven't managed to fix this yet. Any help would be appreciated.

Thanks,

Zach Miller

Just put (char) in front of wxT(...), like

   if (tc > 0) {

      wxString wxst1, wxst2;

      wxst1.Append((char)wxT('('));

      for (int i=0 ; i<5 ; i++)

         if (tc & (1<<i)) {

            if (i < 4)

               wxst1.Append((char) (wxT('1'+i)));

            else

               wxst1.Append((char) wxT('E'));

            wxst1.Append((char) wxT('|'));

         }

      for (int i=0 ; i<5 ; i++)

         if (tc & (1<<(i+8))) {

            if (i < 4)

               wxst1.Append((char) (wxT('1'+i)));

            else

               wxst1.Append((char) wxT('E'));

            wxst1.Append((char) wxT('&'));

         }

      if (wxst1.Length() > 0)

         wxst1 = wxst1.Left(wxst1.Length()-1);

      wxst1.Append((char) wxT(')')); 

 Hi Stefan,

Thanks for the response. I have tried that and it fixes all the lines except the ones that have:

wxst1.Append((char) (wxT('1'+i)));

Those lines still don't compile for me. I've also tried: wxst1.Append((char) (wxT('1'+(char)i))); and wxst1.Append((char) (wxT((char)'1'+i))); as well as a few other combinations of (char) and Append.

I get the same error of: "Call of overloaded "Append(int)" is ambiguous."

Any other help would be greatly appreciated. Thanks!

-Zach

wxst1.Append((char) (wxT((char)('1'+i))));     maybe ??? 

 Aha!

wxst1.Append((char) (wxT('1'+i)));

That one actually works as you initially thought, but you my editor was being picky of (char)wxt... instead of (char) (wxt....). For some reason, it has to have the extra set of parentheses around wxt(). Thank You!

Hi,

Our group had previously heard that a "DRS-5.0" might be on the horizon and that it may have ethernet capabilities as well as 16-input channels (we heard this when ordering the DRS-4). Is this still in the works and accurate information? If so, is there a rough estimate to the "release date?"

Thanks for your time,

Zach Miller

You mix up two things: The DRS5 chip is a new device with improved samling speed (10 GSPS) and lower dead time. This chip might come in 2-3 years. The 16-input board you mentioned is a DAQ board based on the DRS4 chip. This board well be operational beginning of 2013 as a prototype. It is not clear however at this point in which way this board will be made available for public. Maybe we will license this to industry. The design is however pretty much defined: 16 channels with gain 0.1-100, 1 GHz Bandwidth, Gigabit Ethernet output, and multi-board capabilities. Trigger on each channel with logical combinations. 80 MSPS continuous sampling (in addition to the DRS4 sampling). Each channel can be biased 0-210 V for SiPMT or APD power. A 19" 3 HE crate will host 16 boards with 256 channels.

/Stefan

 Thanks, Stefan. That was the information we were looking for.

Cheers.

-Zach

Hello,

what is the abbreviation of DRS?

Thanks and kind Regards,

Moritz

Domino Ring Sampler. 

Hi,

    We are using drs4 board, but oscilloscope app will somehow stop to work if we config trigger into "or and", When I look into the drs4 firmware file drs4_eval3_app.vhd, I couldn't find the trigger_config value assignment which is mentioned at(#7 offset 0x1E from 31 downto 16) in manual_version 4.

could you help me find this trigger_config access point? Or is there any drs4_eval4_app.vhd missing in the source files?

thanks

Hongwei

The "and" in the trigger section means now "coincidence". So the V4 board can trigger on a coincidence between two or more channels. If there is no pulse at the same time on the coincidence channels, the board will of course not trigger. The according firmware was introduced in V4, so please look at drs4_eval4_app.vhd (not eval3).

I just realized that the V4 firmware might be missing in the distribution, so I have attached it here. Look for drs_ctl_trigger_config.

Best regards,

Stefan

 Ah, great, that helps, Thank you!

Hongwei

 By the way, will there be a drs4_eval4.vhd as well?

 Here it is.

 Thanks. have a good day

 I have some question according to GetWave function. In drs_exam.cpp simple GetWave(0,0,wave_array[]) etc...is used. Is there primary (cell) calibration, secondary calibration (Readout) and remove Spikes used, as in DRS Oscilloscope application?

 Yes, yes, no. To get spike removals, you need the function RemoveSpikes from Osci.cpp in the DRSOsc project.

 Hi.

I have 2 DRS4 evaluation V4 boards, and I want to use these 2 board to multi board DAQ system for 4 ch vs 4 ch DAQ.

But there is no option for multi board use. I just only find the multi board trigger mode check button on DRS4 Oscilloscope program, but I couldn`t check. 

Is there any method to use multi board?

Best regards.

Gyuhee.

This mode is not yet implemented in firmware. Maybe I find some time towards the end of this year to add this. At the moment, you have to build and external trigger to synchronize the two boards. There are also 16-channel boards on the market where you would not need a multi-board mode. Just Google for "DT5742".

/Stefan

 Thanks Stefan.

I will build external trigger system. 

I made a pre-compiled package for Mac OSX 10.8 (Mountain Lion), so one should be able to install the DRS Oscilloscope software with one mouse click on a recent Mac.

The Makefile in the tar ball now also supports OSX 10.8, so one could even compile it from the sources on a Mac, after libusb-1.0 and wxWidgets have been installed. That might then also work on older versions of OSX.

In addition, the software has been adaptes so that it compiles nicely on a Raspberry Pi (http://www.raspberrypi.org), a screenshot has been attached. Together with a Raspberry Pi and an old screen, the evaluation board is one of the cheapest available oscilloscopes.

 Hi.

I asked about using multi boards some days ago, and I got answer to use external trigger. (Thanks Stefan!)

And here is another question. I made two external triggers and try to acquire coincidence data using two boards. but DRS Oscilloscope program can connect only one board and don`t acquire both of them simultaneously.

So I tried to use two computer for each board separately, but, well, you already know, I failed to acquire because two computers don`t promise to synchronize the two boards acquisition.

Is there any method to solve this problem?

1. I want to acquire coincidence data from the two DRS 4 Evaluation board V4 simultaneosly.

2. I have external trigger to provide the two boards at the same time.

3. How can I get data from the two boards?

Best regards.

Gyuhee.

You have to write your own program. DRS Oscilloscope does not (yet) support this. Take drs_exam.cpp as a starting point and try to extend it to two boards. One tricky point is that the external trigger may only fire AFTER the two boards have been read out. So you need some means of re-enabling the external trigger after you read out both boards.

Stefan 

That`s very bad news for me. I don`t have much time to study & write C programming...

Anyway, Thank you very much Stefan.

Best regards.

Gyuhee.

When Denable and Dwrite is high , the voltage of PLLOUT is 0 V.  And  the Dtap is turn high with no delay when the Denable turns high.

After power up and configuration(the WSR,WCR,CR are all set to 11111111), the readout data is no change whenever the input analog signal and rofs,bias,oofs changes. I have test useing the DAC to supply the Dspeed voltage, and change a new DRS4 chip, but all is the same. The readout data is strange : the first about 100 cells is rise or fall  and the last 900 cells is out of the range of ADC.

So how should I do for debugging the drs4 now.

The first thing to make work is to have DTAP oscillating with fsamp/2048. Keep Denable and Dwrite low (required during power-on, see elog:10), set Dspeed to 2.5V, then rise Denable and Dwrite. You should see Dtap toggling at about 2.4 MHz. If not, double check all supply voltages, and especially all soldering points. The QFN package is a bit hard to solder.

/Stefan 

 "Keep Denable and Dwrite low (required during power-on, see elog:10), set Dspeed to 2.5V, then rise Denable and Dwrite. You should see Dtap toggling at about 2.4 MHz. "

In this process ,  should i config any registers( WSR,WCR,CR  ) ?

After power-up reset, these registers are all set to "1", which should be ok to start.

BTW, Jinhong Wang <wangjinh@mail.ustc.edu.cn> from your institute hast the chip correctly working. Maybe he can help you in a more direct way than I can.

How to configure DRS oscilloscope for the oscillations with an amplitude greater than the value of the exposed
in the trigger (internal). 

Sorry, I don't understand that question. The DRS4 Evaluation board input signal range is 1V. If you have larger signals, you have to attenuante them externally.

/Stefan 

Can I adjust the internal trigger DRS oscilloscope for signal extraction 0.5 volts (for example) from any of the four channels. In our case, there is a lot of noise with low amplitude, which must be removed during the registration. We need to record the individual pulses of higher amplitude than the noise. So we want to use the internal trigger DRS oscilloscope to cut this noise by setting up its threshold amplitude noise.

 Sure, you can set the trigger level with the vertical slider (see attached figure). The trigger level works form -0.5V to +0.5V. Just like with a normal oscilloscope. I thought this would be obvious...

    That's it? Thank you for your comprehensive answer.

 I switched from rev 3 to rev 4 board, but have some problems with triggering, board is now waiting for trigger (rev.3 is working). How to do in drs_exam.cpp for example triggering on Ch0 && CH1 ?

Software 4.0.0, windows version.

Here is old trigger initialisation: 

b->EnableTrigger(0,1);

b->SetTriggerSource(0);

b->SetTriggerLevel(0.25, false);

b->SetTriggerDelayNs(0);

Btw. Is it possible to set up different trigger Levels for each channel ?

(If there is some interest here is my code in Qt, still aplha) http://sourceforge.net/p/qtpals/code

Sorry the late reply.

In V4, triggering has changed. You can trigger now on an OR or AND of channels. Therefore you have to supply a bitmask, where the 1st bit = CH1, 2nd bit = CH2 and so on. Have a look at the most recent drs_exam. It contains code:

   /* use following lines to enable hardware trigger on CH1 at 50 mV positive edge */
   if (b->GetBoardType() == 8) {     // Evaluaiton Board V4 
      b->EnableTrigger(1, 0);           // enable hardware trigger
      b->SetTriggerSource(1<<0);        // set CH1 as source
   } else {                          // Evaluation Board V3
      b->EnableTrigger(0, 1);           // lemo off, analog trigger on
      b->SetTriggerSource(0);           // use CH1 as source
   } 

So if you want CH1 && CH2, you look at the source code of SetTriggerSource. It contains

      // Set trigger configuration
   // OR  0=CH1, 1=CH2, 2=CH3, 3=CH4, 4=EXT
   // AND 8=CH1, 9=CH2, 10=CH3, 11=CH4, 12=EXT

So an AND between CH1 and CH2 needs a

    b->SetTriggerSource(1<<8 | 1<<9);

Your code looks interesting. Do you have a screenshot or can you explain what it does? 

Hi Stefan,

A quick question, what is the typical variation of the sampling capacitors in DRS4?  Will this variation be significant to affect your sampling result?

 Best,

Jinhong

The capacitors sample the input voltage, not the charge, so the actual size of the capacitors does not matter on first order (the variations might be in the order of 5%). A bigger effect is the variation of the analog switches in the front of the capacitors, which is about 15%. So the actual bandwidth each cell sees varies by maybe 20% (given by the R and the C), but this comes only into play when sampling steep edges.

Stefan

 Great to know this! Thanks~

Jinhong

 Hi Dr. Stefan,

So the sampling capacitors store the input voltage instead of the charge. What about the readout circuits? I saw there is a buffer followed each sampling capacitor. Do you buffer the charge (like a charge sensitive amplifier)  or the voltage? From Fig.12, 14 in datasheet, it seems most probably the readout is a charging or discharging of a capacitor. Could you please add some comments on this? 

Cheers,

Jinhong

The buffer buffers the voltage, not the charge. The curves in Fig. 12, 14 indicate that the voltage followers take some time until they settle. 

Stefan

 Are there any plans to include reconstruction of nonuniform sampling  in DRS4 to get uniformly sampled data?

Im now reading article IEEE Trans on Circ. ans Systems I, Vol.55 No.8 sept. 2008 Reconstruction of Nonuniformly Sampled Bandlimited Signals Usinga Differentiator–Multiplier Cascade by Stefan Tertinek and Christian Vogel

and plan to implement it, but may be somebody has it done before me.

Interesting paper. I was not aware of this method. Sounds interesting. AFAIK, nobody has implemented it so far.

My (old) plan was to linearly interpolate samples (something you could do in an FPGA as well), but this will introduce (small) errors. The next best thing would be to do some spline interpolation, but this is time consuming and not suited for an FPGA.

If you get good results with the method above, please let others know about it.

/Stefan 

I need to synchronize two signals. These signals have a different polarity.

I can set triggers on different levels. But I can't set different polarity of triggers.

Now I can set (T1 and T2), I need to set (T1 and (not T2))

Is it possible?

d->SetTriggerLevel(-0.4,0.4,0.0,0.0,false);

d->EnableTrigger(1, 0);  // Enable trigger

d->SetTriggerSource(1<<8 | 1<<9);  // T1 and T2

file DRS.cpp:

int DRSBoard::SetTriggerLevel(double voltage1,double voltage2, double voltage3,double voltage4,bool negative)

{

…

      SetDAC(fDAC_TLEVEL1, voltage1/2 + 0.8);

      SetDAC(fDAC_TLEVEL2, voltage2/2 + 0.8);

…

There is no way to select different polarities, it is not implemented in the firmware. Like your digital oscilloscope has also only one polarity switch.

The only way to do it is to use a (passive) inverter, so that you have two signals of the same polarity. Something like this:

http://www.phillipsscientific.com/pdf/460ds.pdf

Hi,
I am considering using the DRS4 evaluation board as an ADC card for the wire chamber in the physics lab (VP) experiment at ETH. However, the wire 
chamber has 8 outputs, so I would need to have two of such boards. Is it possible to synchronise them, online or offline? From the website, it looks 
like yes, but the documentation says that these features (trigger and clock out) may not have been implemented in firmware yet. Could you tell me 
the status?

Thank you very much,

Dmitry.

> Hi,
> I am considering using the DRS4 evaluation board as an ADC card for the wire chamber in the physics lab (VP) experiment at ETH. However, the wire 
> chamber has 8 outputs, so I would need to have two of such boards. Is it possible to synchronise them, online or offline? From the website, it looks 
> like yes, but the documentation says that these features (trigger and clock out) may not have been implemented in firmware yet. Could you tell me 
> the status?
> 
> Thank you very much,
> 
> Dmitry.

I'm right now working on it. If you only need 2-3 ns accuracy  between the two boards then you can do this already now without firmware upgrade. The software for this is in principle ready, but I have to 
finish the documentation. Since I'm on a business travel right now this might take me some time (weeks?). 

If you want better timing (O(100ps)) between the boards, then you will need a firmware update. Or you wait until we ship boards with the new firmware. I will announce this through this forum.

Stefan

When starting Chip Test in DRS Command Line Interface, I receive the following message:

Cell error on channel 1, cell 5: -154.4 mV instead 0 mV

Chip Error!

What does this mean? The maximal peak-to-peak Amplitude given to channel was for a short time 10V.

The graphical interface shows no artefacts when using channel 1.

The "Chip Test" command is made for a special test board we use for chip testing. This command will not work with the evaluation board, since only four of the 8 DRS channels are connected there. So just ignore it and verify the board functionality by looking at the graphical interface.

/Stefan 

I have noticed some differences in the source code between Windows (4.0.0) and Linux (4.0.1) Version.

drs_exam.cpp: In the windows version when setting the trigger there is no part "if (b->GetBoardType() == 8) {...} else {...}" like in Linux version. So under Windows drs_exam does not start readout of DRS 4 Evalutation Board V4, because it does not get the trigger, under linux the board can be read out succesfull. I have found out, that adding the missing part solves the problem for the windows version.

drs.cpp (Windows Version), line 2101, function "int DRSBoard::SetTriggerDelayNs(int delay)":

There is no operation which  calculates the variable "fTriggerDelayNs" out of variable "ticks" like in function "int DRSBoard::SetTriggerDelayPercent(int delay)" (Line 2073). So "fTriggerDelayNs" can get diverse values when using one of the Trigger Setting Functions. Was this intended?

Thanks for reporting the problem in drs_exam.cpp. The windows and linux versions sometimes differ a bit. I'm working right now on a complete new version, wich will bring both together again.

Concerning fTriggerDelayNs and ticks, they are correlated. One tick is a single delay unit in the FPGA. On the newest boards the unit is 4.8ns long. So

ticks = fTriggerDelayNs / 4.8

fTriggerDelayNs = ticks * 4.8

fTriggerDelayNs gets set at the first line of SetTriggerDelayNs:

int DRSBoard::SetTriggerDelayNs(int delay)
/* set trigger delay in nanoseconds */
{
   short ticks, reg;
   fTriggerDelayNs = delay;

So I cannot see how fTriggerDelayNS should get diverse values?

 Hi,

Does anyone has a program that converts a binary file from drsosc  output to a ROOT tree format?

Thank you,

Dmitry.

Hi Stefan,

Is either some example code or a detailed written description available for the improved DRS4 timing-calibration algorithm described by Daniel Stricker-Shaver at MIC 2012?  I think you told me that you had verified the results with your own test set-up, so I figure there must be at least two sets of code in existence to implement this calibration.  (I have Daniel's presentation slides.)

I managed to find a ping-pong distribution of cell widths that looks quite similar to that shown in Daniel's slides, using an algorithm similar to the technique one uses to find radial offsets in a tracking chamber (i.e. using residuals weighted by track slope), but I'd rather use the method with which you and Daniel have already found good results.  (The attached graph shows in black the histogram of cell widths for essentially the algorithm used in DRS.cpp/DRSBoard::AnalyzeWF, and in blue the histogram of cell widths extracted from the slope-weighted residuals for a periodic reference signal.)

By the way, since Daniel finds a FWHM coincidence-timing resolution around 20-25ps at 5 GSPS (for perfectly identical pulses), should I expect a FWHM resolution (for synthesized, ideal pulses) of around 50-65ps at 2 GSPS?

(I'm posting here instead of writing you both privately because I figure there may be broader interest in Daniel's algorithm.)

-Bill

Hi Bill,

there are several reasons why we have not yet published Daniel's method (I'm in constant contact with him).

1. The method still changes, becomes simpler and more accurate. Originally he used sine waves with varying frequency, which you only get from an external function oscillator. Currently, we found that a single frequency could do a similar, maybe even better job. The current result is much better than the 20-25ps quoted at MIC 2012.

2. Daniel found out that for the ultimate resolution you have to calibrate each channel inside a chip separately. I do understand in meantime the reason for that. So I plan for a V5 evaluation board, which contains means of sending a log-jitter clock to all channels. This board is in test phase and will be made available once it's working as expected.

So my plan is to finish the V5 board and implement the best possible timing calibration on it. Daniel achieved already <5 ps RMS (!) independent of the delay between the two optimal pulses (up to 50 ns). This is actually better than what you can do with a high-end oscilloscope, since scopes have internal interleaving and similar problems due to aliasing etc. than the DRS chip, but scope manufacturers do not put such an emphasis on accurate timing measurements. Once we can reproduce the 5 ps result with the evaluation board, we will publish it. When we found the optimal method, we plan to write a paper about it and explain everything in great detail. We will also be at Seoul for MIC 2013. I'm topic convener there for the session "Digitalization, Acquisition, and Signal Processing Technologies". So probably we will put the DRS4 timing talk there, since it's of more general interest not only to medical applications (and honestly, for a 150 ps TOF-PET you do not need a 5 ps electronics resolution). So stay tuned!

/Stefan

Hello!
let me apologize in advance if this has already been covered somewhere and I missed it. 

I have a question about a statement made regarding the ADC clock in the evaluation board v4.0 manual.  At the bottom or page 23 there is a mention of jitter between the SRCLK signal and the ADC clock causing a baseline variation in the sampled output of up to a few mV.  Is there any more information out there about this?  I find this confusing for the following reason: If the DRS output has mostly settled after 28ns and the signal that is being sampled is a DC signal, I don't understand why an aperture jitter in the sampling ADC should cause a voltage error in the measured signal.  I already know about the possibility of noise spikes every 32 samples if these clocks are not properly aligned, though I don't know the origin of those spikes.  are these two things related?

Many Thanks!
 

Hi Benjamin,

In principle you are right, for a DC signal that should not matter. But in reality the DRS4 output signal is not constant even for a DC signal. When you switch from one sampling cell to another during readout, there is something called "charge injection". This causes the output to change up to several 10 mV. After 28 ns this is mostly settled, but not completely, since the DRS4 output driver has a relatively low bandwidth (~50 MHz). Furthermore, the signal line between the DRS4 and the ADC is not terminated, so you have some reflections going forth and back. In addition, you have some crosstalk from the SRCLK signal. So it's better that you sample on each cycle at exactly the same time. Here you see a plot of that (green: DRS4 output, blue: ADC clock, yellow SRCLK):

Hi,

I would like to use the DRS4 with my macbook pro running osx 10.6.8.
I have installed the wxWidgets and the libusb-1.0 libraries and I am using the Linux code vers. 4.0.1. After
compilation, the following errors come out:

ld: warning: in musbstd.o, file was built for unsupported file format which is not the architecture being linked
(i386)
ld: warning: in mxml.o, file was built for unsupported file format which is not the architecture being linked (i386)
....
....
ld: warning: in main.o, file was built for unsupported file format which is not the architecture being linked (i386)
Undefined symbols:
  "_main", referenced from:
      start in crt1.10.6.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
make: *** [drsosc] Error 1


Do you have any idea on how to solve the problem ?? or maybe do you have a package working with osx 10.6 ? I
remember to have seen, long time ago, a package that could work with 10.6 (or 10.5 ?), but I cannot find it now
(but maybe I remember wrong).

Thanks for any help,

Enrico

> Hi,
> 
> I would like to use the DRS4 with my macbook pro running osx 10.6.8.
> I have installed the wxWidgets and the libusb-1.0 libraries and I am using the Linux code vers. 4.0.1. After
> compilation, the following errors come out:
> 
> ld: warning: in musbstd.o, file was built for unsupported file format which is not the architecture being linked
> (i386)
> ld: warning: in mxml.o, file was built for unsupported file format which is not the architecture being linked (i386)
> ....
> ....
> ld: warning: in main.o, file was built for unsupported file format which is not the architecture being linked (i386)
> Undefined symbols:
>   "_main", referenced from:
>       start in crt1.10.6.o
> ld: symbol(s) not found
> collect2: ld returned 1 exit status
> make: *** [drsosc] Error 1
> 
> 
> Do you have any idea on how to solve the problem ?? or maybe do you have a package working with osx 10.6 ? I
> remember to have seen, long time ago, a package that could work with 10.6 (or 10.5 ?), but I cannot find it now
> (but maybe I remember wrong).
> 
> Thanks for any help,
> 
> Enrico

Can it be that you have a old PowerPC MAC? I have no experience with that, but probably you have to adjust the Makefile
ans set some flags correctly for PPC instead of Intel.

/Stefan

> 
> Can it be that you have a old PowerPC MAC? I have no experience with that, but probably you have to adjust the Makefile
> ans set some flags correctly for PPC instead of Intel.
> 
> /Stefan


No, I have a MacBook Pro 2.8 GHz Intel Core 2 Duo.

> Hi,
> 
> I would like to use the DRS4 with my macbook pro running osx 10.6.8.
> I have installed the wxWidgets and the libusb-1.0 libraries and I am using the Linux code vers. 4.0.1. After
> compilation, the following errors come out:
> 
> ld: warning: in musbstd.o, file was built for unsupported file format which is not the architecture being linked
> (i386)
> ld: warning: in mxml.o, file was built for unsupported file format which is not the architecture being linked (i386)
> ....
> ....
> ld: warning: in main.o, file was built for unsupported file format which is not the architecture being linked (i386)
> Undefined symbols:
>   "_main", referenced from:
>       start in crt1.10.6.o
> ld: symbol(s) not found
> collect2: ld returned 1 exit status
> make: *** [drsosc] Error 1
> 
> 
> Do you have any idea on how to solve the problem ?? or maybe do you have a package working with osx 10.6 ? I
> remember to have seen, long time ago, a package that could work with 10.6 (or 10.5 ?), but I cannot find it now
> (but maybe I remember wrong).
> 
> Thanks for any help,
> 
> Enrico

it looks like 64bit vs 32bit problem, you have to compile all libraries for the same architecture. Maybe, make clean to 
remove all precompiled object files .o and recompile it again. Try to compile first that simple example without wxWidgets.

Martin

> 
> it looks like 64bit vs 32bit problem, you have to compile all libraries for the same architecture. Maybe, make clean to 
> remove all precompiled object files .o and recompile it again. Try to compile first that simple example without wxWidgets.
> 
> Martin


Good point, but all libraries are already compiled to 32 bits, since the laptop is running at 32 bits. Unless you mean that I
have to convert to 64 bits, but this means to change all content of the PC, and I don't want to do this. Can the applications
run with 32 bits or do they need 64 ? 

Thanks,
Enrico

> > 
> > it looks like 64bit vs 32bit problem, you have to compile all libraries for the same architecture. Maybe, make clean to 
> > remove all precompiled object files .o and recompile it again. Try to compile first that simple example without wxWidgets.
> > 
> > Martin
> 
> 
> Good point, but all libraries are already compiled to 32 bits, since the laptop is running at 32 bits. Unless you mean that I
> have to convert to 64 bits, but this means to change all content of the PC, and I don't want to do this. Can the applications
> run with 32 bits or do they need 64 ? 
> 
> Thanks,
> Enrico

There is no specific reason to run it on 64 bits, so just all libraries have to match, that's all. But the original Makefile has been written for 64 bits, so it might need some 
adjustments.

/Stefan

> > > 
> > > it looks like 64bit vs 32bit problem, you have to compile all libraries for the same architecture. Maybe, make clean to 
> > > remove all precompiled object files .o and recompile it again. Try to compile first that simple example without wxWidgets.
> > > 
> > > Martin
> > 
> > 
> > Good point, but all libraries are already compiled to 32 bits, since the laptop is running at 32 bits. Unless you mean that I
> > have to convert to 64 bits, but this means to change all content of the PC, and I don't want to do this. Can the applications
> > run with 32 bits or do they need 64 ? 
> > 
> > Thanks,
> > Enrico
> 


> There is no specific reason to run it on 64 bits, 

Good.

> so just all libraries have to match, that's all. But the original Makefile has been written for 64 bits, so it might need some 
> adjustments.

Ok, but I don't understand where is the point to correct. 64 bits do not appear explicitally (at least to me, who am not a drake of programming ...) 
neither in the Makefile neither in the (few) source files I have examined.

Thanks again,
Enrico

> > > 
> > > it looks like 64bit vs 32bit problem, you have to compile all libraries for the same architecture. Maybe, make clean to 
> > > remove all precompiled object files .o and recompile it again. Try to compile first that simple example without wxWidgets.
> > > 
> > > Martin
> > 
> > 
> > Good point, but all libraries are already compiled to 32 bits, since the laptop is running at 32 bits. Unless you mean that I
> > have to convert to 64 bits, but this means to change all content of the PC, and I don't want to do this. Can the applications
> > run with 32 bits or do they need 64 ? 
> > 
> > Thanks,
> > Enrico
> 
> There is no specific reason to run it on 64 bits, so just all libraries have to match, that's all. But the original Makefile has been written for 64 bits, so it might need some 
> adjustments.
> 
> /Stefan

Hi Stefan,
   I made some progress. Understood what was wrong in the make phase. You have only to add the option -arch i386 in the CFLAGS line of the makefile.
Then the make is ok, it produces the 3 executables. drs_exam and drscl seem to work correctly. 
DRSOsc.app does not work as app, in the sense that if you click it, an error message comes saying "You can't use this version of the application DRSOsc.app with 
this version of Mac OS X. You have Mac OSX 10.6.8. The application requires Mac OS X 10.7 or later. "
If you execute drsosc from the terminal, the graphical window pops up, the waveform is displayed, but you don't have access to the graphical interface, no button works, you can't do
anything. To quit the app, you have to kill it from the terminal with the kill command.
But anyway is a progress with respect to yestarday.
Any idea/suggestion to overcome the above problems ? I thought it is a problem with the graphical library (xwWidgets) but I have checked it, it's ok, I have also reinstalled it
(release 2.8.12_3) but nothing changed.

PS. the chip test output (done with the drscl ) is the following (see below). Is it normal or what ? THANKS.

B0> ct
Press 'q' to quit, any other key to repeat test.

Max. frequency is 5.1 GHz
Cell error on channel 1, cell 5: -137.6 mV instead 0 mV
Chip Error!

Max. frequency is 5.1 GHz
Cell error on channel 1, cell 5: -129.4 mV instead 0 mV
Chip Error!

> I made some progress. Understood what was wrong in the make phase. You have only to add the option -arch i386 in the CFLAGS line of the makefile.
> Then the make is ok, it produces the 3 executables. drs_exam and drscl seem to work correctly. 
> DRSOsc.app does not work as app, in the sense that if you click it, an error message comes saying "You can't use this version of the application DRSOsc.app with 
> this version of Mac OS X. You have Mac OSX 10.6.8. The application requires Mac OS X 10.7 or later. "
> If you execute drsosc from the terminal, the graphical window pops up, the waveform is displayed, but you don't have access to the graphical interface, no button works, you can't do
> anything. To quit the app, you have to kill it from the terminal with the kill command.

To run an executable as an app, you have to put it into a certain directory structure. The Makefile has the target "make app" which exactly does that. It executes following code:

DRSOsc.app: drsosc
        -mkdir DRSOsc.app
        -mkdir DRSOsc.app/Contents
        -mkdir DRSOsc.app/Contents/MacOS
        -mkdir DRSOsc.app/Contents/Resources
        -mkdir DRSOsc.app/Contents/Resources/English.lproj
        echo 'APPL????' > DRSOsc.app/Contents/PkgInfo
        cp drsosc.xcodeproj/Info-processed.plist DRSOsc.app/Contents/Info.plist
        cp drsosc DRSOsc.app/Contents/MacOS/DRSOsc
        cp drsosc.xcodeproj/DRSOsc.icns DRSOsc.app/Contents/Resources

You can also do this manually. You will then see the subdirectly DRSOsc.app actually as an App icon (you don't see it as a subdirectory in the Finder).  That's the way Apple has chosen to do this.

The chip test facility has been made for a certain test board we use for chip testing. It has a feature that is not present in the evaluation board. I have to disable that command there.

Best regards,
Stefan

> > I made some progress. Understood what was wrong in the make phase. You have only to add the option -arch i386 in the CFLAGS line of the makefile.
> > Then the make is ok, it produces the 3 executables. drs_exam and drscl seem to work correctly. 
> > DRSOsc.app does not work as app, in the sense that if you click it, an error message comes saying "You can't use this version of the application DRSOsc.app with 
> > this version of Mac OS X. You have Mac OSX 10.6.8. The application requires Mac OS X 10.7 or later. "
> > If you execute drsosc from the terminal, the graphical window pops up, the waveform is displayed, but you don't have access to the graphical interface, no button works, you can't do
> > anything. To quit the app, you have to kill it from the terminal with the kill command.
> 
> To run an executable as an app, you have to put it into a certain directory structure. The Makefile has the target "make app" which exactly does that. It executes following code:
> 
> DRSOsc.app: drsosc
>         -mkdir DRSOsc.app
>         -mkdir DRSOsc.app/Contents
>         -mkdir DRSOsc.app/Contents/MacOS
>         -mkdir DRSOsc.app/Contents/Resources
>         -mkdir DRSOsc.app/Contents/Resources/English.lproj
>         echo 'APPL????' > DRSOsc.app/Contents/PkgInfo
>         cp drsosc.xcodeproj/Info-processed.plist DRSOsc.app/Contents/Info.plist
>         cp drsosc DRSOsc.app/Contents/MacOS/DRSOsc
>         cp drsosc.xcodeproj/DRSOsc.icns DRSOsc.app/Contents/Resources
> 
> You can also do this manually. You will then see the subdirectly DRSOsc.app actually as an App icon (you don't see it as a subdirectory in the Finder).  That's the way Apple has chosen to do this.
> 
> The chip test facility has been made for a certain test board we use for chip testing. It has a feature that is not present in the evaluation board. I have to disable that command there.
> 
> Best regards,
> Stefan

Hi Stefan,
yes, the makefile has already the recipe to create the app. For OSX 10.6 a obvious modification must be done in the info.plist file. Then everything goes right. Now I have the DRSOsc application
running on my mac with 10.6.
Thanks for the help.
Best regards,
Enrico

Hello Sir,

Regarding to analog pulse counting by using DRS4 Rev.2.0 board, you have said that "There is a way to perform the counting dead time free, but that requires the V4 board, which has a hardware comparator on all four channels (The V2 board has only one comparator and a multiplexer). The output of these comparators go directly to the FPGA, which can then trigger on these signals. In principle one could implement a hardware counter in the FPGA, which works practically dead time free. But this requires a new firmware which has to be written. Either you do it yourself using the Xilinx development tools, or you wait until I find some time to implement this, which could take a couple of weeks or even months."

I am interested in it. I have DRS4 Rev.2.0 board. I have FPGA and Microcontroller firmware for this board. How can I implement this concept of counting pulses?

As I said above, you need a V4 board which has the four hardware comparators mounted. You cannot do that with the V2 board, even with a firmware upgrade.

The firmware upgrade for the V4 board is not yet ready and I won't have time for that in the next 3-4 weeks, but afterwards maybe.

Best regards,

Stefan 

 Thank you for your response.

The DRS4 Rev.2.0 with one Multiplexer and a Comparator I think may be is ok for me. Since I wanted to implement counter in FPGA, I have gone through firmware but its very difficult for me to get the flow of data from DRS to USB. Could you help me to get familiar with or to get flow of the data from DRS to the USB?

Thank You,

Sonal

Hi Sonai,

unfortunately I cannot teach you VHDL, you should take a course somewhere. Actually you don't have to touch the USB part, you just have to implement a new register in the firmware, and connect it to a VHDL counter attached to the trigger input. I will do this in a couple of weeks myself, so you can also just wait. I will however only do this for the V4 board, so you have to port it back to the V2 firmware.

Best regards,

Stefan

Hello, Stefan. Have you implemented pulse counting yet?

Best, Osip.

Nope. 

 Will it be done in the foreseeable future?

Yes. I will announce it in the forum. 

Hi,

while trying to create python bindings for the DRS stuff using SWIG 2.0.4, two undefined methods prevent the python interpreter from loading the generated shared library. These methods are:

• int DRSBoard::SetADCActive(unsigned char)
• bool ResponseCalibration::Calibrate(unsigned int,unsigned int,float *,float *,float,bool)

Can we safely removed those methods from the DRS header files or (what I have actually done) is it better to fake some empty implementation in the input file to SWIG?

Another minor issue is that the python interpreter always terminates with a SegFault after script termination. I had not yet time to track that down...

Thanks & regards

Hermann-Josef

Thanks for pointing that out. My C++ compiler does not complain about such errors. You can safely remove these functions. I did so as well, so future versions will not contain that any more.

/Stefan 

Hi,

I would like to save the waveform in a binary format. When I click Save then change format from xml to dat in the menu. I still get xml format but with dat extension.

what I am missing?

Thank you,

Dmitry.

Version 4.0.1 has a problem there. Please use 4.0.0. If you can compile the program yourself, just change this line:

--- DOFrame.cpp (revision 20656)
+++ DOFrame.cpp (revision 20655)
@@ -517,7 +517,7 @@
       if (!filename.empty()) {
          m_btSave->SetLabel(_T("Close"));
          m_btSave->SetToolTip(_T("Stop saving waveforms"));
-         if (filename.Find(_T(".")) != wxNOT_FOUND) {
+         if (filename.Find(_T(".xml")) != wxNOT_FOUND) {
             m_WFfd = 0;
             m_WFFile = mxml_open_file(filename.char_str());
             if (m_WFFile)

 Thanks that fixed it!

Dmitry

Working with the DRS evaluation board we noticed some funny behavior: See attatchment 1. In about 1% of scope traces we see the first and last bin take on a value substantially different from the baseline, note the small spikes on the end of the traces. These spikes occur across all channels and either appear in all channels or in none. Attachment two shows what several thousand scope traces look like. You can clearly see that some of the traces are offset from the normal base line. Has anyone observed this behavior before? Any ideas?

see https://muon.npl.washington.edu/elog/g2/Detectors/550 for full discussion. 

Actually the first and last sample are even more off the baseline, so I cut them out in software in the DRSOscilloscope. So actually the chip has only 1022 "usable" cells. It might happen in some rare cases that more cells are affected, although I have not yet seen this (maybe I did not look close enough). So I propose that you cut out one more bin at the beginning and the end, so a total of 1020 cells, and you should be fine.

/Stefan 

 Thanks for the quick reply. Our quick fix was to do just that. 

 We've encountered similar issues with board v2.0. Cell #2 across all channels would occasionally go full negative amplitude (0 I guess).

I don't remember if calibration fixed the problem, might have.

Hallo,
I'm using DRS4 Evaluation Board Rev 4.0 and I'm trying to change the output of the samples to be an average of  #  measurements (1000 or even more)
during the process I have encountered some difficulties I hope you will be able to help me  with:

1. the DRS chip have 8 channels but the Evaluation board have only 4 channels. does the default mode of the DRS in the Evaluation Board is 1024 bins for each channel or 2048?

2. in the readout mode, does it samples all the 1024 bins waveform from a channel and then move to the next one, or after each bin it move to the next channel?

3. In the file "drs4_eval4_app.vhd", I have a problem finding the names of the signals that represents the registers bits which tell me what is the number of the bin (1-1024) the ADC is reading from the DRS, and the signals

that represents registers A0-A3. can you send me their names? 

4. In another matter- is the -0.5V to 0.5V is the  upper and lower  limit of the input (or just a working range), and if not what is the limit for AC?  is there a fuse on the board in case of overload from the input? (I didn't see  it in the User's Manual, but I didn't know if you will mention it there in case there is one).

thanks in advance and have a nice day,

Tmiron

1. All 8 channels are read out, but only 4 are displayed in the oscilloscope.

2. It reads all 1024 bins from a channel, then switch to the next channel.

3. The ADC readout happens in lines 1576+. The register for the sample count is drs_sample_count, and the signal for the address is drs_addr.

4. The evaluation board manual explicitly mentions the maximum allowed input range on page 5.

/Stefan 

Thank you for the answer.

Have a nice week,

Tmiron.

 Hi Stefan,

I'm trying to add the averaging feature to the oscilloscope instead. I have a basic knowledge in C++ so I'm having problem finding the initial place (places) of the data acquisition. furthermore, I saw you already made an averaging possibility for some of the features in the program at the measure window.
Can you please tell we in which of the programs of the Scope (and in what line if possible) can I find the initial\main data acquisition so I could follow it from there, and where is the location of the averaging function you already made?

have a nice week,

Tmiron

The averaging possibility in the measure window is just a "place holder" for future extensions, which are not yet implemented.

A good point to implement averaging is in the function Osci::ReadWaveforms() in Osci.cpp.

/Stefan 

I have been trying to compile my changes to the program, but have a problem with the "wxWidgets". can you tell me which version of the wxWidgets and which c++ program did you use to built the drs4's scope program?

I'm using "microsoft visual c++ 2010 express", and the closest I got to compile something was with the wxWidgets 2.8.12 version (It's tell me I'm missing the file "wxmsw28d_core.lib" although I built it).

have a nice day,

Tmiron.

I guess it should work with 2.8.12. Try to compile their examples, and consult their documentation if it does not work. I cannot give support for a package I have not written.

/Stefan 

My problem is not with wxWidgets itself but with links your program is doing to the wxWidgets. if you can please tell me the wxWidget version you used, I'll use this one instead the version I'm using and I think it will solve the problem.

Tmiron.

I currently use version 2.9.4, but chances are high that it will work with 2.8.12.

/Stefan 

 but was version 2.9.4 the one you used when you built  Version 4.0.0 of the DRS4 oscilloscope program, or was it an erilar version, and if so, do you remeber what version it was?

tmiron.

I used 2.8.12 for Version 4.0.0.

/Stefan 

 Hi Stefan.

I managed to add the averaging possibility to the oscilloscope program, but it runs too slow, so now I'm tring to add this option to the example file you attached to the program (drs_exam.cpp).
My problem is that when I run the file is not passing  the stage of getting the trigger. (it just wait after writing the line "Waiting for trigger...")
When testing the software, I work with a signal of up to 10 MHz, limited in voltage to the DRS Eval 4 ability, and I connect the signal to channel 1,from it by default is supposed to get the trigger. I also tried to change the channel settings to other channels or external trigger, and use them,  but it still not working.

I found out that the problem is related to the line "while (b->IsBusy());" in the code, but I have a problem understanding what the function "IsBusy" do and how it's work.

Can you please explain me a bit what this function does?

have a nice day,

Tmiron

The function b->IsBusy() returns true if there has been no trigger. So "while (b->IsBusy());" is simply an endless loop until the board triggered. Please check your signals and trigger configuration. Maybe you have to adjust the trigger level or polarity via b->SetTriggerLevel(). Try signals with lower event rates. Verify that the board triggers with the DRSOsc program, you can then read off the optimal trigger level from there. 

/Stefan

Hi satefan,

I did some debug on the DRSOsc program and saw that everywhere you used the function "IsBusy()", you used it with "SoftTrigger()", which (to my understanding) create a software trigger. did you used another function, other than "ISBusy", that check the hardware trigger?

have a nice day,

Tmiron.

No. IsBusy() is the only way the hardware trigger is checked. If there is no hardware trigger, you can issue a "fake" trigger (called software trigger) to stop the acquisition. This happens for example if you switch DRSOsc to "Auto" trigger instead of "Normal" trigger, very similar than a normal oscilloscope does.

/Stefan 

 hallo stefan,

I managed to fixed the problem. The problem was with the number I inserted to the function "b->SetTriggerSource" th get external trigger (it suppose to be "16" and not "4" or "12" as I understood from the function's comments).

Right now I'm trying to speed up the number of wavefrom  per second. I'm using your  drs_exam.cpp program you wrote as my basic program. When you wrote it you used the function "b->StartDomino()" inside the loop, which means that before every trigger you gave him a command to start the domino-wave.

From  the "DRS4 datasheet" (page 8) I understand that I can bypass the need to restart the  domino-wave by using "b->SetDominoActive(1)" and "b->SetDominoMode(1)", but when I tried it didn't work (the waveform I got every readout remain the same which means the dominowave froze after the first readout).

Am I understanding wrong or do I need to add somthing more\else so the domino-wave will not stop after each readout? is there any hazard by doing that, as mentiond in page 8 of the the datasheet?

thanks again,

Tmiron.

The Domino wave anyhow is always active in mode 1, but you have to enable the writing to the memory cells (via the DENABLE signal). This is done with the b->StartDomino(). You are right that this call takes about 1ms over USB 2.0, so avoiding it would speed up the DAQ by about a factor of two. I have some plans to implement an automatic restart in firmware of the evaluation board, but I won't have time for that until fall of this year.

/Stefan

Is it possible to set sampling frequency at 100 MHz in DRS4 eval board? Trying to set 0.1GHz in Osci program results in around 0.7 GHz. In drscl.exe i'm able to set freq at 0.1GHz but calibration is impossible.

Thank For Help!

Andrzej Rychter

700 MHz is the minimal sampling frequency. If you need 100 MHz, just buy a "normal" commercial ADC.

Best regards,

Stefan 

 OK!

Thanks for fast reply.

Andrzej

Hi,

I wish to interface the DRS4 with the 8-channel ADC AD9222 (or AD9637).

I'm reading from the DRS4 datasheet that "the analog output of the DRS4 chip has been designed to match directly the input of the AD9222". OUT+ output of DRS4 is in the range from 0.8V to 1.8V and OUT- output is shifted by the voltage applied to the O-OFS pin.

The span of the AD9222 ADC core is defined by REFT and REFB which are resp. 1.4V and 0.4V in a typical case (AVDD=1.8V, VREF=1V). My understanding is that the ADC analog inputs must be within the voltage range defined by REFT and REFB and so I don't quite see how this matches the DRS4 outputs.

Can we use the full-scale range indeed? Do we have to use AC-coupling with mid-supply bias? What is the point I missed?

Thank you for your help.

  Hello everyone！I'm a new user of DRS4 board,but it seems that some files are missing in my demo project.So I hope someone could help me by sending a correct VHDL hardware project to my Email:lcyiss900@gmail.com.Thanks in advance!

T

 I checked my project today and I think I need the file USR_LIB_VEC_IOFD_CPE_NALL.I don't know if is it a VHD files or a IP core.

I'll be extremely grateful.

 USR_LIB_VEC_IOFD_CPE_NALL is defined in firmware/srs/usr_lib.vhd which is part of the software package.

Hi,

I have install drs software on ASUS EeeBox with Ubuntu 12.04 LTS. When I try to use ./drsosc the oscilloscope window flickers. Can you suggest what might be the problem?

Here is some more info:

******************************************************

System:

Ubuntu 12.04 LTS

Memory: 992.9 MiB

CPU: Intel Atom CPU N270 @ 1.6GHz x 2

32 Bit

Disc: 156.5 GB

***************************************

Software:

Due to version Ubuntu I had to install the wxWidgets from source (wxWidgets with x11)

Thank you,

Dmitry.

This problem is new. Even on a slower Raspberry Pi we did not see any flickering. Have you tried a different version of wxWidgets? 

yes the problem was in wxWidgets, I have downgraded the ubuntu version and installed packaged version of wxWidgets. Now it works without problems.

Thank you,

Dmitry. 

 I installed Mac OS package on macbook (late 2013). DRSOsc starts to write file but freezes; need to be restarted to restore connection with DRS4 evaluation board (ordered Aug 2011). 

When I ran from the command line, I see these messages:

phone$ /Applications/DRSOsc.app/Contents/MacOS/DRSOsc

2013-11-18 15:11:31.278 DRSOsc[96539:507] CoreText performance note: Client called CTFontCreateWithName() using name "Lucida Grande" and got font with PostScript name "LucidaGrande". For best performance, only use PostScript names when calling this API.

2013-11-18 15:11:31.279 DRSOsc[96539:507] CoreText performance note: Set a breakpoint on CTFontLogSuboptimalRequest to debug.

2013-11-18 15:11:31.281 DRSOsc[96539:507] CoreText performance note: Client called CTFontCreateWithName() using name "Lucida Grande" and got font with PostScript name "LucidaGrande". For best performance, only use PostScript names when calling this API.

2013-11-18 15:11:31.283 DRSOsc[96539:507] CoreText performance note: Client called CTFontCreateWithName() using name "Lucida Grande" and got font with PostScript name "LucidaGrande". For best performance, only use PostScript names when calling this API.

2013-11-18 15:11:31.285 DRSOsc[96539:507] CoreText performance note: Client called CTFontCreateWithName() using name "Lucida Grande" and got font with PostScript name "LucidaGrande". For best performance, only use PostScript names when calling this API.

0 - 0.250

1 - 0.250

2 - 0.250

3 - 0.250

0 - 0.250

1 - 0.250

2 - 0.250

3 - 0.250

2013-11-18 15:11:32.933 DRSOsc[96539:507] CoreText performance note: Client called CTFontCreateWithName() using name "Lucida Grande" and got font with PostScript name "LucidaGrande". For best performance, only use PostScript names when calling this API.

...

...

and these:

musb_write: requested 10, wrote 0, errno -4 (Unknown error: -4)

musb_read error 0

musb_write: requested 10, wrote 0, errno -4 (Unknown error: -4)

musb_read error 0

...

...

I tried to compile Linux package, but got error messages:

drs-4.0.1$ make

cc -g -O2 -Wall -Wuninitialized -fno-strict-aliasing -Iinclude -I/opt/local/include -DOS_DARWIN -DHAVE_USB -DHAVE_LIBUSB10 -DUSE_DRS_MUTEX -c src/musbstd.c

cc -g -O2 -Wall -Wuninitialized -fno-strict-aliasing -Iinclude -I/opt/local/include -DOS_DARWIN -DHAVE_USB -DHAVE_LIBUSB10 -DUSE_DRS_MUTEX -c src/mxml.c

In file included from src/mxml.c:79:

include/strlcpy.h:27:14: error: expected parameter declarator

size_t EXPRT strlcpy(char *dst, const char *src, size_t size);

             ^

/usr/include/secure/_string.h:105:44: note: expanded from macro 'strlcpy'

  __builtin___strlcpy_chk (dest, src, len, __darwin_obsz (dest))

                                           ^

/usr/include/secure/_common.h:39:62: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                                                             ^

/usr/include/secure/_common.h:30:32: note: expanded from macro '_USE_FORTIFY_LEVEL'

#    define _USE_FORTIFY_LEVEL 2

                               ^

In file included from src/mxml.c:79:

include/strlcpy.h:27:14: error: expected ')'

/usr/include/secure/_string.h:105:44: note: expanded from macro 'strlcpy'

  __builtin___strlcpy_chk (dest, src, len, __darwin_obsz (dest))

                                           ^

/usr/include/secure/_common.h:39:62: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                                                             ^

/usr/include/secure/_common.h:30:32: note: expanded from macro '_USE_FORTIFY_LEVEL'

#    define _USE_FORTIFY_LEVEL 2

                               ^

include/strlcpy.h:27:14: note: to match this '('

/usr/include/secure/_string.h:105:44: note: expanded from macro 'strlcpy'

  __builtin___strlcpy_chk (dest, src, len, __darwin_obsz (dest))

                                           ^

/usr/include/secure/_common.h:39:53: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                                                    ^

In file included from src/mxml.c:79:

include/strlcpy.h:27:14: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]

size_t EXPRT strlcpy(char *dst, const char *src, size_t size);

             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/usr/include/secure/_string.h:105:44: note: expanded from macro 'strlcpy'

  __builtin___strlcpy_chk (dest, src, len, __darwin_obsz (dest))

                                           ^~~~~~~~~~~~~~~~~~~~

/usr/include/secure/_common.h:39:31: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                              ^~~~~~~~~~~~~~~~~~~~~

In file included from src/mxml.c:79:

include/strlcpy.h:27:14: error: conflicting types for '__builtin___strlcpy_chk'

/usr/include/secure/_string.h:105:3: note: expanded from macro 'strlcpy'

  __builtin___strlcpy_chk (dest, src, len, __darwin_obsz (dest))

  ^

include/strlcpy.h:27:14: note: '__builtin___strlcpy_chk' is a builtin with type 'unsigned long (char *, const char *, unsigned long, unsigned long)'

/usr/include/secure/_string.h:105:3: note: expanded from macro 'strlcpy'

  __builtin___strlcpy_chk (dest, src, len, __darwin_obsz (dest))

  ^

In file included from src/mxml.c:79:

include/strlcpy.h:28:14: error: expected parameter declarator

size_t EXPRT strlcat(char *dst, const char *src, size_t size);

             ^

/usr/include/secure/_string.h:111:44: note: expanded from macro 'strlcat'

  __builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))

                                           ^

/usr/include/secure/_common.h:39:62: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                                                             ^

/usr/include/secure/_common.h:30:32: note: expanded from macro '_USE_FORTIFY_LEVEL'

#    define _USE_FORTIFY_LEVEL 2

                               ^

In file included from src/mxml.c:79:

include/strlcpy.h:28:14: error: expected ')'

/usr/include/secure/_string.h:111:44: note: expanded from macro 'strlcat'

  __builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))

                                           ^

/usr/include/secure/_common.h:39:62: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                                                             ^

/usr/include/secure/_common.h:30:32: note: expanded from macro '_USE_FORTIFY_LEVEL'

#    define _USE_FORTIFY_LEVEL 2

                               ^

include/strlcpy.h:28:14: note: to match this '('

/usr/include/secure/_string.h:111:44: note: expanded from macro 'strlcat'

  __builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))

                                           ^

/usr/include/secure/_common.h:39:53: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                                                    ^

In file included from src/mxml.c:79:

include/strlcpy.h:28:14: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]

size_t EXPRT strlcat(char *dst, const char *src, size_t size);

             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/usr/include/secure/_string.h:111:44: note: expanded from macro 'strlcat'

  __builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))

                                           ^~~~~~~~~~~~~~~~~~~~

/usr/include/secure/_common.h:39:31: note: expanded from macro '__darwin_obsz'

#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)

                              ^~~~~~~~~~~~~~~~~~~~~

In file included from src/mxml.c:79:

include/strlcpy.h:28:14: error: conflicting types for '__builtin___strlcat_chk'

/usr/include/secure/_string.h:111:3: note: expanded from macro 'strlcat'

  __builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))

  ^

include/strlcpy.h:28:14: note: '__builtin___strlcat_chk' is a builtin with type 'unsigned long (char *, const char *, unsigned long, unsigned long)'

/usr/include/secure/_string.h:111:3: note: expanded from macro 'strlcat'

  __builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))

  ^

2 warnings and 6 errors generated.

make: *** [mxml.o] Error 1

What the best way to build DRSOsc on the Mac OS X?

Thanks,

Andriy.

DRSOsc seems broken on OSX 10.9. I'm working on this right now. Some of the problems are related to wxWidgets, so I'm waiting for a new version running stably under OSX 10.9. The compilation problem related to "strlcpy" comes from the fact that OSX 10.9 now comes with its own version of that function, while all previous versions did not. So simply removing strlcpy.h/c from the project fixes that.

There will be a new version of DRSOsc next month which fixes all this problems, so just stay tuned.

/Stefan