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TMS320F28066: F28066 PWM4 output abnormal issue with SYNC to PWM1 feature

Benjamin Zhou
Expert 4000 points
Part Number: TMS320F28066


Hi Team,

  my customer reported an strange issue for PWM4 output in TMS320F28066PNT after INIT the PWM with the Demo code that the PWM output is abnormal (PWM4A always with Low, PWM4B always with High):

  1. Configure TBCTR = TBPHS in INIT, the PWM 4 can’t output even after SYNC;

  2. Configure TBCTR = 0 in INIT, the PWM 4 can work normally;

  3. If set TBCLKSYNC = 1 before PWM module init, even if the TBCTR = TBPHS, the PWM4 output is normal after first SYNC;

 

Could you kindly support Below items:

  1. Could you confirm the TBCTR = 0 can fixed the PWM4 abnormal issue;

  2. Could you clarify why a) worked?

  3. Could you clarify why TBCLKSYNC set to 1 can fixed the PWM abnormal issue;

Expect for your reply, thanks.PWM initilization cased PWM abnormal issue_F28066.docx

  • 0
    TI__Genius 10820 points

    Hi Benjamin,

    Which demo code are you referring to? Is it a C2000 PWM example code, application kit/reference code or the customer's own code?

    Is PWMSYNC (for PWM4) enabled in the init code? If PWM4 is getting synced by another PWM, is that PWM period equal to PWM4 period? 

    Do they see this issue only on PWM4 or have they observed the same behavior on other PWMs as well?

    Thank you.

    Hrishi

  • 0 in reply to Hrishi Nene
    TI__Expert 4000 points
    Hrishi,
    This issue has found in customer own source code, and then they used the demo code which just do a little modification based on epwm_updown_aq , and the source code customer used has provided in the attached file which is in the end of file post in the upper.
    I'll mail you for this thread, and expect for the further discussion in the mail. thanks.

    Best Regards
    Benjamin
  • 0 in reply to Benjamin Zhou
    TI__Genius 10820 points

    This issue has been resolved over e-mail by modifying usage specific PWM initialization routine.