FADC Data Format June 9, 2015

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Location and Time

Room: CC L207 ??

Time: 2pm.

Remote Connection

(if problems, call phone in conference room: 757-269-6460 might not be the correct number)

  1. To join via Polycom room system go to the IP Address: (bjn.vc) and enter the meeting ID: 589693655.
  2. To join via a Web Browser, go to the page [1] https://bluejeans.com/589693655.
  3. To join via phone, use one of the following numbers and the Conference ID: 589693655
    • US or Canada: +1 408 740 7256 or
    • US or Canada: +1 888 240 2560

More information on connecting to bluejeans is here

Specific instructions for connecting via polycom:

  • Turn polycom on if necessary
  • With the polycom, place a call at
  • Press # to enable the polycom keypad, then enter the meeting id: 589693655 and #
  • You may have to unmute the microphone: #*4
  • Turn the computer on if needed


Useful Links


Present: Naomi (CMU), Cody, Elton, David, Beni (JLab)

  1. Cody is still finding a few signals which do not make timing (ie the signal needs more than one clock cycle to get from one state to the next, the delays can be due to excess logic or routing or both) in the full version of the new firmware, where all the possible output quantities are calculated and then selected for output according to the data format mode in use. More than 80% of the FA125 resources are in use; this is after redoing the daisy-chaining and back-end.
  2. However, the code for just one readout format - the CDC combination mode - does make timing. This needs to have the configuration parameters finalized and Cody will ask Bryan for the readout library so that he can test it (the library supplies the register space for the configuration parameters and the data decoder). Cody asked about doing full crate tests to check the trigger rates, Beni said yes, do this as soon as he can.
  3. Cody will keep working on the full version. If it does not seem likely that this will be successful, the backup plan is to make separate firmware versions for the CDC and FDC.
  4. The timing algorithm has been fully pipelined, with every loop removed. XTHR_SAMPLE and NSAMPLES can be configurable. Naomi: we are ok with NSAMPLES constant.
  5. Naomi: We can remove the tests for overflow and upsampling errors as these can be identified offline.
  6. Naomi has been looking at prototype data to see if XTHR_SAMPLE should be configurable (probably, yes) and if using a mean of a number of samples for the timing pedestal gives better results than a single sample (so far, no, but needs further work).
  7. Naomi mentioned reducing the upsampling factor. This would not help with synthesis (making timing), but would make the process finish sooner.
  8. Elton mentioned that the FA250 team are planning to revise their firmware and might adopt some similar tactics to the FA125's.
  9. Lubomir asked about the FA125 self-triggering. Cody will look to see how long this would be likely to take to implement.