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TMS320F28379D: EPWM phase shift

Hung Kai Woo1
Intellectual 825 points

Part Number: TMS320F28379D

Hi 

 

I am using a phase shift feature of EPWM. I have a question. In Period setting of EPWM, there is shadaw register for update it. I am not sure that in phase shift register TBPHS will be updated immedialy or it updated as PWM in zero-cross

  • 0
    TI__Expert 3340 points

    Hi Hung,

    For the C2000 microcontroller's EPWM module, the TBPHS (Time-Base Phase Shift) register does indeed have shadow register functionality, similar to the period register. The update behavior is controlled by the TBPHS load mode settings.

    TBPHS Update Behavior

    The TBPHS register is not updated immediately when you write to it. Instead, it follows the shadow register update mechanism specified by the TBPHS load mode bits (PRDLD) in the Time-Base Control Register (TBCTL):

    • When configured for "shadow" mode (default setting), TBPHS values are loaded from the shadow register to the active register at the following events:
      • Counter equals zero (CTR = 0) in up-count or up-down-count modes
      • Counter equals period (CTR = TBPRD) in down-count mode
    This means that phase shift changes are synchronized with the PWM waveform transitions to prevent glitches or unexpected behavior.
    Key Points to Remember

    1. Shadow Register Behavior: TBPHS updates occur at specific synchronization points (typically counter zero), not immediately upon writing to the register.

    2. Synchronization Control: You can control this behavior using the Time-Base Control Register settings.

    Thanks

    Srikanth