Adding CAN to the Raspberry Pi
It is very easy to add a CAN interface to the Raspberry Pi using the MCP2515 CAN controller.
Note that the Raspberry Pi only supports 3.3V I/O. Placing 5V signals on input pins will damage your Raspberry Pi. The MCP2515 will run fine on 3.3V but you need to leave the CAN tranceiver running at 5V.
A very nice instruction with all steps can be found on https://www.raspberrypi.org/forums/viewtopic.php?t=141052