[Bug Fix] Corrected bug in nominalDacScalingFactors

[bdorney]

Description

In QC7 we noticed that for some VFATs the DAC scan for CFG_HYST would always fail to find a valid value; after some discussion in person with VFAT3 designers we determined that the value for the scaling factor needs to be updated.

Types of changes

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

Motivation and Context

So inside some DACs there is a factor that is inside the DAC itself that will change the input current/voltage; this current/voltage that the DAC actually uses is not accessible by either ADC when making a DAC scan but it is related to the actual current used by the fixed factor.

VFAT3 designers admitted this isn't very well described in the manual; but we went through and cross-checked each of the scaling factors.

It was found that only CFG_HYST was in error and it should be noted that for CFG_CAL_DAC the value we have in the nominalDacScalingFactors dictionary is only valid for the voltageStep injection mode and is not valid for the currentPulse mode.

How Has This Been Tested?

Change was trivial

Checklist:

• [ ] My code follows the code style of this project.
• [ ] 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.

[bdorney]

How do you want to treat the CFG_CAL_DAC depending on the pulse mode?

Considering it's harder to convert voltage to charge than current to charge I disabled the scanning of CFG_CAL_DAC from the voltage buffer. See:

https://github.com/cms-gem-daq-project/cmsgemos/blob/48e2f269dac0947be0101d2a9f0d943752e2ce61/gempython/tools/hw_constants.py#L17-L44