CAN Bus

Setting up the CAN bus is based on this tutorial.

Kernel-wise the following needs to be added to the /boot/config.txt

dtparam=spi=on
dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=25
dtoverlay=spi0-hw-cs

This should work most of the time, however in recent Raspberry Pi firmware builds there happened to be a problem with this approach. A solution to the problem was described here. The solution utilizes the pinout program which can be installed using sudo apt-get install python3-gpiozero. Using this program the BCM number is read and then used in the /boot/config.txt as follows.

dtparam=spi=on
dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=25
dtoverlay=spi-bcm{BCM_NUMBER}

For example:

dtparam=spi=on
dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=25
dtoverlay=spi-bcm2837

Reboot is required after for the /boot/config.txt to take place.

To debug problems with the SPI or the MCP2515 use dmesg | grep spi.