CAN / CAN FD Bus

CAN / CAN FD Bus is the dominant protocol for networking electronics in vehicles. It features a bit rate up to 1 Mbit and offers simple networking of microcontrollers with the help of dedicated CAN / CAN FD bus silicon called a CAN / CAN FD Controller.

The data transfer message of CAN / CAN FD is the data frame. This data frame is allowed to have a longer ID and is then called an extended data frame.

Used in some applications but not in automotive is the remote frame. The remote frame allows a node to request a particular CAN / CAN FD ID.

CAN / CAN FD is very robust. This means it can not only detect many errors but can take action such as automatic transmission or node shut down.

CAN / CAN FD uses the bit stream to resyncronize the receivers to the transmitter. In order for this to work with specific bit sequences CAN / CAN FD must use bit stuffing. Bit stuffing makes decoding a CAN / CAN FD waveform on a traditional oscilloscope difficult.

CAN / CAN FD is a data link layer. To signal CAN / CAN FD electrically there are three common physical layers in use.

In some applications where CAN / CAN FD is used FlexRay or LIN may provide advantages.

The CAN / CAN FD bus Specification from Bosch: can2spec.pdf

A CAN / CAN FD Bus Data Frame.