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Commissionning of the Herschel FE Crate

Timing scan

Dan please document

ADC conversion factor measurement

To redo

Triggering the L0 sequence from external input and reading RAM

The L0 sequence generated by the CROC can be triggered from an external source by sending a -800mv pulse on the "Trig L0 Seq" input of the CROC front plane. This can replace the manual triggering of the L0 Sequence which is done by pressing the "Trigger L0 Seq" button of the CROC panel.

Setup description

The external signal is generated from a waveform generator. In order to have the crate and generator sharing the same clock, the waveform generator recieve a 20MHz clock from the CROC through the "clock div" output of the CROC front plane. By default the divided clock has a 1Hz frequency. This can be set to 20MHz in the CROC CAT panel by setting Clock-->Div to 2 instead of 40000000 and pressing Apply.

The generator provide a single pulse of 25ns width, with a -800mV amplitude. This output is directed to "Trig L0 Seq" input of the CROC front plane.


Setup the CROC (clock origin and RAM spying configuration), and fill the FE RAM (for detailled procedure, see "Hands-on CAT and the boards"). Prepare the required L0 Sequence. The "L0 Delay" can be used to delay the start of the L0 sequence from the N clock count after the board receive the signal that trigger the L0 sequence.

On the FE panel:

  • Press the ChannelB-->Calibration button (this tells the FE to be ready to send the RAM?)
On the CROC panel:
  • Press the General Control--> Enable Seq button. This tells the spyRAM to get ready to receive a L0 sequence. (validL0seq function of croc spyPGA)
  • Launch the triggerring of the L0Sequence from the generator.
  • Press the Spy-->Transfer-->Start and then Spy-->Transfer-->View

In this configuration the result is not different from what one would get from just pressing the "Acquisition" button but the internal logic is different: Acquision correspond to pressing "Enable Seq","Trigger L0", "Start" and "View", where "Trigger L0" launch the L0 sequence. Here we replace "Trigger L0" by the pulse from the generator.

Sending data from a waveform generator and spying them in the CROC SpyPGA

This setup that can be used to test the behaviour of integration + digitisation of an input signal by FE, especially for testing the response to a long train of data when the DAQ is not available.

The waveform generator provides two inputs:

  • an analog input which fakes the PMT signal. We test the case were N clock counts contains large signal and the N+1 one contains no signal.
  • a pulse to trigger the L0 sequence

The L0 sequence is set to 15 consecutive trigger (which is the maximum we can spy), with a frequency of 0 (a trigger every bunch) The L0 Sequence should reach the FE with a delay allowing the SpyRAM to see the data around the N+1 bunch crossing. This delay can be tunned using the L0 delay.

Synchronisation of the channels in DAQ

Victor please document

Synchronisation of the channels in Trigger


-- VictorCoco - 03 Oct 2014

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Topic revision: r2 - 2014-10-03 - VictorCoco
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