Suggestions to add to stim board.

[jharvey]

Suggestion to add a MUXed voltage reference which can be used to validate that each op-amp's measurement circuit is operating properly. Something similar to the below could be a added to one of the MUXed inputs allowing the Nucleo to validate that the opamp circuit has not been damaged or validate the opamp circuit is preforming badly for some reason.
https://jlcpcb.com/partdetail/Onsemi-TL431BVLPRAG/C513084

Also suggest to add LED"s to the TC4427, this would allow to validate that the TC4427 is attempting to drive either high or low.

[rusefillc]

@jharvey there is that amazing https://xyproblem.info/ convention:

The XY problem is asking about your attempted solution rather than your actual problem.

within that convention I see Others try to help user with Y, but are confused because Y seems like a strange problem to want to solve.

so, WHY?