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TMS320F280049: eCAP/ePWM sync function question

Huihuang Chen
Expert 4010 points
Part Number: TMS320F280049

Hi Champ,

 I have two question for eCAP/ePWM sync function as following:

1.if eCAP6 configure to use EXTSYNCIN1 as sync input, and configure GPIO0  as EXTSYNCIN1 through input XBAR.

how many SYSCLK delay from the GPIO0  rising edge to the CTRPHS be load to TSCTR? this delay clock is fixed or not fixed?

2. Based on my testing ,if eCAP6 enable HRCAP function, the EXTSYNCIN1 sync function cannot work, but if I disable the HRCAP function,  the EXTSYNCIN1 sync function can work normally. May I know the reason？

3.If ePWM1 configure to use EXTSYNCIN1 as sync input, and configure GPIO10 as EXTSYNCIN1 through input XBAR.

how many SYSCLK delay from the GPIO10  raise edge to the TBPHS be load to TBCTR? this delay clock is fixed or not fixed?

  • 0
    TI__Guru 52020 points

    For EPWM, you are going through the INPUTXBAR, so the delay is not fixed.

  • 0
    TI__Genius 15385 points

    Hi,

    Response to your questions:

    1. It may vary, I will need to check with our design team to confirm. Are you using GPIO0 in synchronous mode?

    2. When you say EXTSYNCIN1 function does not work when eCAP6 is configured as High Resolution CAP (HRCAP), what do you mean? Are you not seeing TSCTR counter initialize to 0 when EXTSYNCIN1 signal comes? Can you provide more details on configuration and what is failing?

    Best Regards,

    Nirav

  • 0 in reply to Nirav Ginwala
    TI__Expert 4010 points

    Hi Nirav,

    used GPIO0 as asynchronous mode.

    Please also check the eCAP EXTSYNCIN1  delay.

    If enable HRCAP, the CTRPHS value be load to TSCTR  never happened but the EXTSYNCIN1  pulse always exist.

    But if disable the HRCAP , CTRPHS  value can  load to TSCTR normal when EXTSYNCIN1  rising edge arrived.

    In the TRM have following description, this Input synchronization means GPIO input qualification Synchronization to SYSCLKOUT or the eCAP module synchronization  function?

    if it is  means the eCAP module synchronization function not supported  in HRCAP mode？could you advise the detail reason?

  • 0 in reply to Huihuang Chen
    TI__Expert 4010 points

    Hi Champ,

    Any feedback about my question?

  • 0 in reply to Huihuang Chen
    TI__Genius 15385 points

    Hi Chen,

    While using HRCAP the HRCLKNTR runs on HRCLK which is asynchronous to SYSCLK, hence input synchronization is not possible.

    I am still waiting on delay numbers from design team. In the meantime may I know what is the relevance of delay in customer used case? Delay numbers will not be deterministic and can be off by few cycles. 

    Best Regards,

    Nirav