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TCAN4550-Q1: Communication fail after changing data rate and message rate

Gabriel Xu
Intellectual 2145 points
Part Number: TCAN4550-Q1
Other Parts Discussed in Thread: TCAN4550

Hi Team

Customer is using TCAN4550 in their new design.

The external crystal oscillator is 20Mhz. Data rate set to 500kbps and the message rate set to 1Mbps the communication is normal.

But if we change the data rate to 500kbps and message rate to 2mbps, the communication fail.

Prescaler ： Rawvalue 1  Registervalue 0
Prop+Phase1： Rawvalue 7tq  Registervalue 6
Phase2： Rawvalue 2tq  Registervalue 1 

The relative software code is shown below:

  • 0
    TI__Guru 53575 points

    Hi Gabriel,

    Thanks for bringing this info to E2E. 

    This configuration for 2Mbps here looks correct. The distribution of time quanta in each of these segments is good and the included functions for the actual configuration have worked well for me in the past for a variety of CAN speeds (including 2Mbps), so this should all be fine as long as it has not been modified. 

    It's likely that the failure in communication occured based on some system characteristic from the CAN bus, something that would create a CAN error that is recognized by the TCAN4550. Can you read the interrupt registers (address = h0820 and h0824) from the CAN controller and let us know what errors are being reported? This could help us pinpoint exactly what the transceiver has recognized as invalid during communication. Additionally, scope shots of the CANH and CANL signals may help us see if this may be caused by some signal integrity issues, possibly due to ringing. 

    Let me know if you have any questions in the meantime. 

    Regards,
    Eric Schott