The problem is when you change the write config register from 11111111 to 01111111, or from 00001111 to 00000111, then the last 256 sampels of the previous channel (in the first case #0, in the scond #4) would be overwritten as soon as dwrite =1 again. So you loose 1/4 ef each channel.

Concerning the readout, indeed you can keep track in the FPGA, but only with a certainty of a few cells. This gives some timing inacccuracy of maybe 10-20 ns, which certainly would be disturbing you.

If I may trouble you for a little more information, the critical point then is that there should not be any zeroes in the write config register while the sampling is active?  In case it was unclear I would only be reading out once sampling was stopped (dwrite = 0).  

As for the readout, I know that I would have to read out all 1024 samples each time, and keep track of where each channel stopped in the FPGA.  I would never know the exact cell where sampling stopped but I hoped that if I discard some number of cells on each side of the expected stopping point that I would be OK.  

Thanks again

The issue with "stopping at cell 767" would also affect this mode of operation. Furthermore, the DRS4 chip has only 10 bit register which records in which cell the event has occured, and where the readout must be started. If you record 8 separate events, you don't know where to start the readout.

The DRS5 chip will have all this possibilitied, but unfortunately it won't be ready before 2-3 years from now.

Stefan

Hello,

I have a question about using the write config register to enable/disable sampling on the fly.  I am looking to instrument an experiment at EPFL where multiple short events need to be captured during a 20us period followed by an 80us quiet period during which we could read out the chip.  Would it be possible to start an acquisition with all channels seeing the same signal and the write config register set to 111111111 and then shift a zero into the write config reg after each event is detected to freeze the channels in time one-by-one?  In this way we could measure up to 8 different events during the active period and then read them all out together during the quiet period.  I have read the posts about the simultaneous read-write mode and the issue with waveforms stopping at cell 767.  not knowing the exact details of what causes this issue I wonder if it would effect this sort of operation?  Also, I would like to know if dwrite must be de-asserted while the write config register is being updated or if it could be done while the sampling is active?  The latter would obviously be preferable as we would not incur any dead-time during the active period.

Thanks in advance for the information,

Benjamin LeGeyt

Hello everybody,

I get often asked if the DRS4 evaluation board can accomodate negative input pulses going to -1V. This is unfortunately not possible, since the board is mainly for evaluation of the DRS4 chip and should not be seen as a complete oscilloscope with flexible input stage. So the maximum it can do is -0.5V to +0.5V or 0V to 1V. For -1V signals, one can use however a passive inverter like this one:

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

And for signals going furhter (-2V, -10V) one can use a passive attenuator like this one:

http://www.pomonaelectronics.com/pdf/d4108_K5513_101.pdf

Best regards,

Stefan

1. Simultaneous writing and reading is not possible with the DRS4 chip. The manual says differently on p. 14, but due to a bug in the chip waveforms get clipped at the end if one does that. We hopt to fix this problem in a future version of the chip.

2. You can cascade 2,4 or 8 channels. If you cascade 8 channels and run at 1 GSPS, you digitize a window of 8 us. If you have 16 signals, you then need 16 chips.

/Stefan

Hi

I want to use DRS4 to digitize 16 channels of signals. The width of signal is about 20 ns, with frequency of 50Hz. The time differences between these 16 signals are not constant, arranging from 3us to 0. I am confused about this in some aspects.

1. Can I use SIMULTANEOUS WRITINT AND READING to realize this? I saw the VHDL program, and if I understand it correctly, it did not work at this state.
2. Or sampling at 1GSPS, using CASCADING OF CHANNELS, I can sample signal at most 4us or 8us, then digitizing all signals of one chip. Have you tested 4 or more channels cascading before?

Besides, any advice will be helpful!

Thank you.

Hi

I want to use DRS4 to digitize 16 channels of signals. The width of signal is about 20 ns, with frequency of 50Hz. The time differences between these 16 signals are not constant, arranging from 3us to 0. I am confused about this in some aspects.

1. Can I use SIMULTANEOUS WRITINT AND READING to realize this? I saw the VHDL program, and if I understand it correctly, it did not work at this state.
2. Or sampling at 1GSPS, using CASCADING OF CHANNELS, I can sample signal at most 4us or 8us, then digitizing all signals of one chip. Have you tested 4 or more channels cascading before?

Besides, any advice will be helpful!

Thank you.

I cannot confirm the story with the "stop capacitor > 767". It can be seen from your plots that the distribution of stop cells are even, no holes or bins with double height.

There is an issue with cell 767, but this is when one tries to do simultaneous reading/writing to the chip. This does not really work as writen in the data sheet. Waveforms sometimgs get cut off at cell 767. But the stop cell is always correct, otherwise one could not calibrate the data. If you use the evaluation board for example, which is perfectly calibrated, and introduce an "artifical" shift like

if stop cell > 767 then
  stop cell = stop cell + 1

then you would see that the voltage calibration would become wrong and very noisy.

Stefan

Hello Stefan,

some colleages told me a story, I was neither able to confirm nor find anything in the datsheet about. According to them:

For some internal reason of the DRS4, if the “stop capacitor” of the DRS4 is >= 767, the true stop channel is one before the stop channel read from the DRS4. In other words, the stop channel which returns the DRS4 shifts after sampling to the capacitor ID 766.

Can you confirm that, or even say a few words about that matter?

I wanted to confirm this by plotting the stop cell distribution for random triggered data, taken with one of the FACT boards. I assumed (possibly misunderstanding the matter), that this would lead to missing values in the area of stop cell 767, but cannot see any significant excess or lack of entries in that area.

Dear Maksat,

If your car does not run, and you call the car dealer and tell him "my car does not run", what will the car dealer ask you? Eh... ? Right ! He will ask "what are the symptoms, what did you try, what did and what did not work". Here it's the same. "was not able to get it work" is not a valid statement, since I have absolutely no idea what did not work and what you did try.

The official way is to follow the instruction in the evlauation board manual on section 2.4 - Installation under Linux. If that does not work, please be a bit more precise what errors you get.

Cheers,
Stefan

Can you tell me (screendump) what is the problem on the web site https://www.psi.ch/drs/software-download ? It should redirect you to

https://www.dropbox.com/sh/qul1cgtm4x7zx13/AADKQ-qGQGdAHPu6OR3vTNY0a?dl=0

for the Windows download.

I cannot send executables via email, that won't go though any spam filter.

Stefan

Hi

 I can't download the software for windows on this website 'www.psi.ch/drs/software-download', there is some mistake when i click on download. 

 If convenient, can you send the software Version 5.0.5 for windows to me? My E-mail address is 'yuhaiyang421@163.com'. Thank you!

Best Regards

Yu

Bonjour, Je suis en stage dans un laboratoire ou on utilise pour echantillonnage des données, une cartes DRS4 5GSPS avec 1024 cell, mon probléme réside dans la partie Calibration en tension selon l'article "Novel Calibration Method for Switched Capacitor Arrays Enables Time Measurements with Sub-Picosecond Resolution". 

En fait je ne comprends pas précisément ces 3 parties de la calibration en tension. Quelqu'un pourras t-il s'il vous plait m'expliquer assez clairement avec des exemples comment il faut s'y prendre? 

Merci et bien Cordialement. 

Dear Stefan,

I am trying to setup DRS inside radiation enclosure and would like to write a simple script that will automatically save certain number of events.

Could you please point to me an example that can I use for Mac OS? I saw there is drs_exam.cpp in the directory but was not able to get work in Mac OS. Any help would be greatly appreciated.

Thanks

Hi Stefan

Any chance you have time to fix the software for multiboard configuration with 2048 samples each. I tried 5.0.5, but drsosc still shows only half of the waveform.

Dmitry

A new software version 5.0.5 has been released today. This fixes a few bugs in multi-board configurations, and adds saving of the scaler values into XML and binary files. Please note that the binary file format has been changed for that. The new format is described in an updated manual (page 25), and reflected in a new read_binary.cpp program contained in the distribution.

/Stefan

The DRS4 chip has been designed to work best at high sampling speeds. At 700 MSPS, the chip is at it's limit and timing is very poorr (ns?). In order to get good timing, run it at least at 2 GSPS.

Stefan

I am studing some pulses that are about 200-300 ns wide and a rise time of few ns,    which settings would be best for coincidence time measurements?

In some preliminary work I found for 700 MegaS the time measurement is better without time calibration (in -0.05 to 1V) rather than with time calibration in -0.5 to 0.5,  my pulses are about 60 mV.   Is it expected that always with time calibration time accuracy would be better or depends?   

Also I use this code snippet to find time for channel 1 and the same idea for chan. 2.

// find peak in channel 1 above threshold
      for (i=0 ; i<1022 ; i++)
         if (waveform[0][i] < threshold1 && waveform[0][i+1] >= threshold1) {
            tt1 = (threshold1-waveform[0][i])/(waveform[0][i+1]-waveform[0][i])*(time[0][i+1]-time[0][i])+time[0][i];
            break;
         }

Thanks!

Abaz

The serial number has been fixed by using drscl. Thank you！