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AM2634: Please let me know related to AM2634 CAN module

YoonJin Kim
Prodigy 110 points
Part Number: AM2634

Hi, Supporter,

I would like to know something related to AM2634 CAN module

Q1. I would like to know AM2634 CAN physical layer using PLL or not.

Q2. And if using PLL, Does CAN transmit and receive the CAN message when the PLL is locked?

Q3. Does CAN support Single Sample Mode? is this default sample mode? or Does CAN support other mode also? How to set/configure 1(single)-sample mode?

Q4. Does CAN support no priority inversion? if yes, is there any configuration parameter to this? or Is AM2634 CAN support this feature automatically based on HW?

If there is documentation related to this, please share it also. It would be more helpful understand.

  • 0
    TI__Guru*** 135355 points

    Hello YoonJin,

    YoonJin Kim said:
    Q1. I would like to know AM2634 CAN physical layer using PLL or not.

    Yes, most peripherals will derive their clocks from the PLL.

    YoonJin Kim said:
    Q2. And if using PLL, Does CAN transmit and receive the CAN message when the PLL is locked?

    This question doesn't make a lot of sense to me. The PLL being locked means that it is stable and ready for use. You would always want the PLL to be locked before using it to source a peripheral like CAN. In any case, the direct answer is yes the CAN transmits and receives when PLL is locked.

    YoonJin Kim said:
    Q3. Does CAN support Single Sample Mode? is this default sample mode? or Does CAN support other mode also? How to set/configure 1(single)-sample mode?

    I am not familiar with the terminology 'Single Sample Mode' - can you elaborate what that mode is supposed to reflect? This is not a terminology I have seen associated with TI microcontrollers using CAN.

    YoonJin Kim said:
    Q4. Does CAN support no priority inversion? if yes, is there any configuration parameter to this? or Is AM2634 CAN support this feature automatically based on HW?

    I will have to check into this further, I don't see any mention of supporting this feature thus far. Let me verify if that is the case.

    Best Regards,

    Ralph Jacobi

  • 0 in reply to Ralph Jacobi
    Prodigy 110 points

    Hi, Raloph,

    Thank you for your feedback.

    Related to Q3,

    • normally there is 1-sample mode and 3-sample mode. This means that methodology how to sampling the data from the CAN message.
      If 1(Single)-sample mode, we have 1 sampling points and we takes the data at the end of TSeg1. In case of Triple(3)-sample mode, we have 3 sampling points and we takes the data at the end of TSeg1 also.
      I didn't see any comments regarding this in the documentation. Please let me know. If AM2634 support two type of sample mode(1 and 3), how to configure it. 

    Related to Q4,

    • I will wait your feedback.
  • +1 in reply to YoonJin Kim
    TI__Guru*** 135355 points

    Hello YoonJin,

    YoonJin Kim said:
    Q4. Does CAN support no priority inversion? if yes, is there any configuration parameter to this? or Is AM2634 CAN support this feature automatically based on HW?

    I got confirmation that this is not a feature we have included in the hardware.

    YoonJin Kim said:
    normally there is 1-sample mode and 3-sample mode. This means that methodology how to sampling the data from the CAN message.
    If 1(Single)-sample mode, we have 1 sampling points and we takes the data at the end of TSeg1. In case of Triple(3)-sample mode, we have 3 sampling points and we takes the data at the end of TSeg1 also.
    I didn't see any comments regarding this in the documentation. Please let me know. If AM2634 support two type of sample mode(1 and 3), how to configure it. 

    I see, thank you for the detailed explanation. I learned something new with this. For AM26x, it is only Single Sample Mode. The past MCUs I worked with were the same, so I was not aware a 3-sample mode existed and how it worked in relation to TSeg1.

    While there is not two types of sample modes to select from, presuming that 3-sample mode is used to help with bit errors, there is a method to check for bit errors revolving around using a 'Secondary Sample Point' (SSP). The TRM has details for this under 13.4.1.4.3.4 Transmitter Delay Compensation - I'd post them here but the Figure in the TRM is key to understanding how it works.

    I hope this clarifies the functionality of the MCAN peripheral sufficiently for you.

    Best Regards,

    Ralph Jacobi