Unexplained intermittent CAN / 2CAN Jaguar problems at GSR

[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.

[techhelpbb]

Originally Posted by Mike Copioli

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.

Thanks you just saved me some time.

I've been looking at various ways to put a little extra capacitance on the 5V and 3.3V sides to increase the noise rejection.

I thought I saw this in the Jaguar schematic before, but I haven't had time to look.