...
Liam suggested this could be a SPI mode issue, but the pins were correct on the current sense LTC6820. However, we realized that the AFEs use a different SPI mode, so the BMS carrier AFE LTC6820 was configured to take input with SPI mode 3 instead of mode 1, which was what we were sending. So in the end, changed the SPI mode, then re-ran the smoke test, and got the expected response. All’s well that ends well I suppose.
Upon running the smoketest and updating some of its bit math, things work well! we get really pretty precise readings (within 10 mA) with the eload connected directly via current sense to the power supply.
Note that in this picture the vrev mv is 2500, it’s just truncated when it prints in minicom
...