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TCAN1046V-Q1: CAN for UART

Jared Becker
Genius 11845 points
Part Number: TCAN1046V-Q1


Hi Team,

If the TCAN1046V-Q1 is being used as CAN for UART, then a user needs to be aware of dominant timeout. A large number of consecutive dominant bits or very low data rates can cause the dominant timeout to trigger for the transmitter and/or receiver, forcing the output to recessive. 

Is this the recommended minimum baud rate for uart to prevent the dominant timeout 9.2kbps?

Also, would the TX UART need to constantly send some sort of keep alive data to the transceiver at a minimum of 9.2 kbps to prevent the CAN from going into DTO?

Thank you,

Jared

  • +1
    TI__Guru 53575 points

    Hi Jared,

    Good question. The minimum data rate on the datasheet describes the lowest rate that can be used for CAN signals. The CAN protocol does not allow more than 5 consecutive bits with the same value. This requirements prevents dominant timeouts from occurring in CAN systems operating at or above this data rate.

    Because UART does not have the same restrictions on consecutive bits at the CAN protocol, the actual minimum data rate will depend on the frame contents. Keep in mind that the dominant timeout only applies to the dominant bit state (logic 0) so an idle UART line which remains recessive (logic 1) will not be subject to any transceiver timeout. Only the number of consecutive dominant bits needs to be considered to avoid the dominant timeout. 

    Let me know if this is clear and if you have any more questions.

    Regards,
    Eric Schott