[Thad House]

Originally Posted by slibert

Fascinating. Congratulations on some nice sleuthing...

Our LabView SPI longevity test has run 16 hours now w/no problems - glad there's an edge case identified we can chase down.

Using the RoboRio Brownout and Understanding Current Draw article as a reference, there are three stages of RoboRio brownout. Do you know which stage was reached in the case you've reproduced? It'd be interesting to know if Stage 2 (which would remove the power from the MXP 5V rail) was hit or not.

Also, could you please post the driver station logs that document the case when this occurs? That should help clarify the details of the scenario. The goal is to try to reproduce this behavior with a benchtop power supply, so the more info on the dynamics, the better. Once reproduced, we can run through various configurations and characterize the behavior more thoroughly.

I will check to see how low the battery voltage was getting when this was happening. I will also get the driver station logs later today. It seems like the NaVX is rebooting, because when we do the RoboRIO code restart, if we do it within 16 seconds, the navx reports its in calibration mode, just like it does on startup.

Note that this for us was not just limited to SPI. I2C had the same issue, but it happened earlier. I would guess that when it happened on I2C, it was because the pullups were being forced high by stage 1. I don't know if SPI has that same issue, but the issue seemed to happen with a much lower battery on SPI then I2C.