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Original question:

CCS: phase shift between ePWMA and ePWMB

CCS/TMS320F28027: CCS: phase shift between ePWMA and ePWMB other than 180 deg

Ruchi Rashmi
Prodigy 50 points
Part Number: TMS320F28027

Tool/software: Code Composer Studio

Dear Richard Poley,

Thanks for providing the clear picture of creating the phase shift between EPWMA and EPWMB on thread

CCS: phase shift between ePWMA and ePWMB

.However, still I have one confusion

1. Is it possible to create 60 deg phase shift between EPWMA and EPWMB using only dead band module ? 

  Since for any phase shift creation other than 180 deg, Maybe, EPWMA has to be passed without any dead band delay and EPWMB should have both delay RED and FED of desired degree, but, I am unable to find this option in the dead module which is referred below. Kindly provide some guidance to create the phase shift between EPWMA and EPWMB other than 180deg using dead band module.

 

  • 0
    TI__Mastermind 27200 points

    Unfortunately it isn't possible to insert both rising edge and falling edge dead-band onto the same PWM output on F28027.  The logic diagram of the DB sub-module on p.243 of the TRM shows what is available on this device.  

    http://www.ti.com/lit/ug/sprui09/sprui09.pdf

    It is possible to do what you require on F28x7x and later devices, but not on F28027.  To obtain 60 degree offset between PWM patterns on F28027 you would need to configure separate PWM modules, synchronize them, then insert the phase shift.  The only exception would be if the duty cycle of one of the patterns was fixed at 50%, in which case the diagram on p.241 of the same document could be used.

    Regards,

    Richard