Advanced PIC18 Projects—CAN Bus Projects:Types of Errors

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Types of Errors

The CAN bus identifies five types of errors:

• Bit error

• CRC error

• Form error

• ACK error

• Stuffing error

Bit errors are detected when the output level and the data level on the bus do not match. Both transmit and receive units can detect bit errors. CRC errors are detected only by receiving units. CRC errors are detected if the calculated CRC from the received message and the received CRC do not match. Form errors are detected by the transmitting or receiving units when an illegal frame format is detected. ACK errors are detected only by the transmitting units if the ACK field is found recessive. Stuffing errors are detected when the same level of data is detected for 6 consecutive bits in any field that should have been bit-stuffed. This error can be detected by both the transmitting and receiving units.

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