Thank you for the help, I looked at the R and D pins on the CAN transceiver and noticed that even though the D line (transmit) was changing the R line was not. It turns out that the Rs pin (mode select pin) on the CAN transceiver was connected to pin 27 (IO16) on the ESP-Wroom-32 module. Adding two ...

Did some more troubleshooting today, it looks like writes to MODULE_CAN->OCR have no effect (always 0). This would explain what I'm seeing, but I don't know why it's happening.

Are there configuration changes that need to be done based on different ESP32 modules for the CAN bus? I'm not able to get any CAN bus functionality to work using the Arduino example from here: http://www.iotsharing.com/2017/09/how-to-use-arduino-esp32-can-interface.html I have this module board whi...