Given this new scenario, what is the maximum rate of events that can be processed then (a rough estimation would be great, 1/2ms?)? is it mainly limited by the USB data transmission and the PC? How does the logic of the trigger and DRS4 data sampling works inside the FPGA in general terms? e.g: trigger activated -> dwrite ON -> ADC acquisition -> busy until data has been shipped off to the PC -> free to process new events.
Is there a way to obtain some sort of timestamp for the trigger on each event? or is it better to use C++ time functions in the PC since the DRS4 is usually used in experiments with low rate of events so the long time it takes to the USB and PC is not a problem? (eg. particle physics).
Thanks for your help,
Matias H.
| Stefan Ritt wrote: |
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The "Trigger OUT" has changed recently. It goes high on a new trigger, but then STAYS high until the board has been read out by the PC and re-started. This allows better synchronization with some external trigger, which can be re-armed with the falling edge of the trigger out signal. The signal can be quite long, since readout of an event via USB typically takes 2 ms, but can be more if the PC is busy. If you need back your 150 ns pulse, send the trigger out to an external pulse shaper with fixed shaping width.
Stefan
| Gerard Arino-Estrada wrote: |
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Hello Stefan,
I am using the DRS4 board connected to a Raspberry PI and through the drsosc application. I am interested on using the "Trigger OUT" signal to do some extra data processing with NIM modules. According to the manual, for each hardware trigger a TTL pulse of 150 ns width should be send through the "trigger OUT". In my case I do see pulses with widths ranging from 100 microseconds up to hundreds of miliseconds. I am connecting the signal directly to an oscilloscope with 50 Ohm termination. I have tried two DRS4 boards in identical conditions and both show the same behavior. Having such wide and variable pulses makes it complicated for me to do the extra post-processing. Have you any idea of what might be going wrong? Thank you very much.
Best regards,
Gerard
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