[DJBecker]

How are you monitoring voltages? Is the microcontroller on the traction voltage side? Or are you using an isolator?

Right now our controller is mixed, with an optoisolator before the gate driver but no isolation if we monitor traction voltages. The MCP3008 A/D converter I mentioned is so that we can put the traction voltage monitoring on its own A/D converter sitting behind a SPI isolator. Isolators such as the Si8441 are under $2 at Digikey, but are only available in SOIC surface mount packages. That's a hassle with our test setup, so isolation will have to wait until we do a circuit board for something else.

Our alternative was using an isolated CAN transceiver such as the TI ISO1050 and leaving the controller at traction voltage. But then we would need to add a body-side controller, with CAN, to send any of the switch information we might use in the future.
We expect to add brake, clutch, neutral, reverse, cruise control and force-idle (e.g. A/C compressor drive) as inputs, and drive the tachometer as a combined motor/battery current/power gauge. Sending that info over CAN might be better in the long run, but right now we don't trust the implementation enough to do more than non-critical reporting.