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TMS320F280049: The method to get PWM falling edge

Rayna Wang
Expert 3680 points

Part Number: TMS320F280049

Hi Expert,

In customer's application, the rising and falling PWM edges are controlled by the below factors in a PWM period

  • Rising edge, is controlled by external signal though CMPSS to PWM.
  • The time interval between falling edge and rising edge need to be 1us to 20us which determined by customer. 

Is there any sub-module could be with PWM to control the falling edge action moment, without too much nesting control loops?

Could ecap, DMA or CLB be used for this function, and could you give some guide lines about the setting steps?

Thanks!

Best Regards

Rayna

  • 0
    TI__Guru 52200 points

    Couple questions followed by some solutions.

    1. The output signal is a one-shot pulse that starts (goes HIGH) with a signal from CMPSS, and then 1-20 us later (based on user setting) with go LOW?

    2. The signal is then repeated when the next signal from CMPSS is generated?

    You can use CMPSS and EPWM. Use the EPWM module to go HIGH and then count for the number of TBCLK cycles you need and pull it LOW.

    1. You will need to set up DCAEVT.sync and DCAEVT.force to both pull the ouput HIGH and SYNC the EPWM module. Then use the CMPA set to the number of cycles needed for 1-20us before it pulls the output LOW.

    2. You could definitely use the CLB as well.

    Nima