Adding modification to GEM data format according to V1

mexanick commented 6 years ago

Description

GEM chamber trailer bits [31:0] were previously unused, but now they include OH EC and BC. As far as I know the bits [19:0] of those 32 bits is OH EC, and bits [31:20] is the OH BC (this depends on the OH firmware, so I'm not 100% sure, but I think it's like that as far as I can see from OH firmware code). GEM chamber header contained 24 bits for zero suppression flags (those are bits [63:40] of the chamber header), but these were never implemented in the firmware due to difficulty figuring out which exact VFAT was actually zero suppressed. What I did in version 1 format is that I added a counter of zero suppressed 64bit words (1 VFAT packet consists of 3 such words). This counter is 12 bits wide and is now sitting in chamber header bits [51:40]. The chamber header bits [63:52] are still unused and are always 0.

Types of changes

[ ] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[x] Breaking change (fix or feature that would cause existing functionality to change)

Motivation and Context

Making data format even with FW implementation

How Has This Been Tested?

not yet tested, need some data

Screenshots (if appropriate):

Checklist:

[x] My code follows the code style of this project.
[x] My change requires a change to the documentation.
[x] I have updated the documentation accordingly.
[ ] I have added tests to cover my changes.
[ ] All new and existing tests passed.

mexanick commented 6 years ago

@evka85 I have a question: am I correct saying that Vwh==Vwt==24*3-ZeroSupWordCnt? Also, what is intended usage of OHBC and OHEC - should we match them to VFAT EC/BC?

jsturdy commented 6 years ago

Would like to have this document updated regularly (every new format version, and am perfectly happy to put it into a better format :-))

cms-gem-daq-project / gem-light-dqm