CAN Level

The driver uses a pair of open drain devices to create a differential signal consisting of CANH (high) and CANL (low) on the bus. Combined, these signals produce the dominant signal level on the bus. The dominant signal level represents a logic low. If no transmitter is driving, pull-up resistors are used to set the bus voltage level to VCC/2. The VCC/2 level is the recessive signal bus level and represents a logic high. During dominant state the active driver configures the CANH line to a high level and the CANL line to a low voltage level. These differential signal levels are typically VCC – 0.9 V for CANH and 1.5 V above ground for CANL.

Pour une vitesse de 250kbits/s, le temps de bit est de 4μs. Lors de l'analyze d'une trace CAN, ne pas oublier de retirer les bits de bourrage (Le bus CAN).

External pull-up resistors can be used to configure the bus for the recessive state. Many CAN bus transceivers have the driver input and receiver output pins passively pulled high internally.