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TCAN4550: data rate is always 1Mbps

Kailyn Chen
Genius 9560 points
Part Number: TCAN4550

Hello,

Our customer used TCAN4550,and read the register CCCR=0X0303, FDOE=1,BRS=1,but the data rate is always 1Mbps whatever configure the data rate is 2Mbps,5Mbps.  That is to say, the data rate couldn't be increased.  Could you please help to analyze? 

Best regards

Kailyn 

 

  • 0
    TI__Mastermind 22965 points

    Kailyn,

    Can you share more about how the device/system is setup & being configured?

    One of the Application Engineers will help follow-up.

  • 0 in reply to Ravi Singh
    TI__Mastermind 33440 points

    Hi Kailyn,

    The INIT and CCE bits of the CCCR register must be set to '1' prior to changing the NBTP and DBTP registers that configure the Nominal and Data phase bit timing.  If the CCCR register eqals 0x0303, then you should be able to set the NBTP and DBTP registers with the new values.  Then you will need to set the CCE and INIT bits in the CCCR register back to '0' before the configuration is complete.

    What is there complete register sequence and values they are writing/reading from the device?  What is the clock frequency they are using?  What Nominal and Data bit rates are they trying to set?

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Genius 9560 points

    Hi Jonathan，

    Thank you for your reply. I have confirmed with the customer, he used the official TCAN linux driver, and the programming sequence has no problem.

     In addition, the data rate of arbitration and data is configured by the latest version of iproute, he checked the status and the data rate has been set 1M, 5Mbps. The clock frequency is 40Mhz.

    Best regards
    Kailyn

     

  • 0 in reply to Kailyn Chen
    TI__Genius 9560 points

    Hi Jonathan，

    Is there any update with this question? Thank you very much.

    Best regards

    Kailyn

  • 0 in reply to Kailyn Chen
    TI__Mastermind 33440 points

    Kailyn,

    The Linux driver has been included into the Kernel and the Linux community is responsible for driver support.  This is a device support forum and I can help you with device specific issues, but I will not be of much help if the issue is with the linux driver.

    I previously asked you to send me the complete register sequence and values they are writing/reading from the device in their configuration sequence.  Can you please provide that so that I can check it for errors? Without this information, I am unable to answer your question.

    I also previously mentioned the required registers and sequence that needed to be followed to change the frequency.

    The INIT and CCE bits of the CCCR register must be set to '1' prior to changing the NBTP and DBTP registers that configure the Nominal and Data phase bit timing.  If the CCCR register eqals 0x0303, then you should be able to set the NBTP and DBTP registers with the new values.  Then you will need to set the CCE and INIT bits in the CCCR register back to '0' before the configuration is complete.


    Can you tell me the value of the CCCR (0x1018), NBTP (0x101C), DBTP (0x100C) and TDCR (0x1048) so that I can check the settings?

    In order to change the frequency settings you will need to do the following:

    Set the INIT (bit 0) and CCE (bit 1) to '1' in the CCCR register (0x1018).  This require a couple of writes to get both the INIT and CCE bits set to '1' because of the protected bit status and CCE can only be set when INIT is equal to '1'.  Therefore the first write sets the INIT bit, but since the INIT bit at the time of write was set to '0' the CCE bit does not take the new value and remains at '0'.  Then a second write to the CCCR register will allow the CCE bit and other bits to take the new values because the INIT bit is '1' at the time of the write.  You have mentioned that the CCCR register was 0x0303, so it appears that the INIT and CCE bits are getting set to allow configuration.

    Once the CCCR register is set to allow initialization and configuration, you can write the new values to the NBTP, DBTP, and TDCR registers for the desired Nominal and FD Data rates.

    Once you have written the new values to these registers (and any other registers in the device), you need to change the INIT and CCE bits back to '0' so that the device exits the initial mode state and enters the normal operation mode.  If you are able to see device transmit data on the CAN bus, then the INIT and CCE bits in the CCCR register should be set to '0' and the CCCR register should be 0x0300. 

    This is the process.  You mentioned "the programming sequence has no problem" so if that is true, the register NBTP, DBTP, and TDCR values must be set incorrectly.  Can you verify that these registers are taking the values that are being written to them?  If the INIT and CCE bits of the CCCR register are not set, the NBTP, DBTP adn TDCR registers will not take the new values and this could point to a sequence issue.  But if these registers are taking the new values, then the NBTP, DBTP and TDCR register values are set incorrectly for the desired bit rates.

    Once you provide me the register specific information, I can check the values for errors.

    Regards,

    Jonathan