Sidecar Brownout causing motors to move

[RufflesRidge]

Originally Posted by sst.thad

We know not to do this, but when it happened all the Talons would turn on backwards for a split second. It this the expected behavior for a sidecar brownout, or do we have a bad sidecar?

Yes, this seems like an expected behavior:

The robot is enabled and you're driving it around. This means that the cRIO is sending PWM signals to the motor controllers via the Digital Sidecar with nominal high pulse width of 1.5ms (neutral) +/- .5ms (forward and reverse respectively). So you're in the middle of sending one of these pulses, and the Digital Sidecar browns out and stops sending the high signal so you have a pulse that is much shorter than what the controller was trying to send.

Some tests we've done with some of our Talons and a pulse-width generator show that they will respond to a signal much shorter than 1.0 ms with full reverse. So your truncated signal is interpreted as full reverse. The Talon then looks for another pulse for a little bit, but doesn't get one so it disables the output.