[Mike Copioli]

Originally Posted by kamocat

What about measuring the thing that actually causes the brownout?
The 3.3v power supply on the Jaguar. What voltage does the processor brown out at? 2.7v?
You can use an interrupt on an analog trigger to wait until a brownout occurs.
(You can get the 3.3v off of the brake/coast pins. If you're using CAN, you can override that jumper anyways)

The brown out on the Jag is around 4.8 volts based on the TPS54040 datasheet. The Jag uses a 5 volt buck in series with a 3.3 v regulator. This is the rated lockout for that regulator, most likely it is above 5 volts. Also the CAN controller and RS232 convertor both operate on 5V volts not 3.3v.