CAN Bus
CAN 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 bus silicon called a CAN Controller.
The data transfer message of CAN 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 ID.
CAN 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 uses the bit stream to resyncronize the receivers to the transmitter. In order for this to work with specific bit sequences CAN must use bit stuffing. Bit stuffing makes decoding a CAN waveform on a traditional oscilloscope difficult.
CAN is a data link layer. To signal CAN electrically there are three common physical layers in use.
In some applications where CAN is used FlexRay or LIN may provide advantages.
The CAN bus Specification from Bosch:  can2spec.pdf
A CAN Bus Data Frame.
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