TMS320F28069M: About dynamically changing the ePWM control registers.

Damith Pavithra

In my code i generate variable frequencies when running, by changing the TBPRD value in a interrupt. Also, i change the action qualifier register configuration in the same interrupt. So my question is, is it ok to change those registers periodically in the running. ?

Thank you

over 6 years ago

0 Richard Poley over 6 years ago

TI__Mastermind 27200 points

You can modify these registers, but you need to be very careful about where in the PWM cycles updates are made. For TBPRD updates, use the shadow mode (TBCTL.PRDLD = 1) to ensure the timer & compare relationship is safely maintained. Also, enable shadow AQ register updates using AQSFRC.RLDCSF for the same reason.

Regards,

Richard

0 Damith Pavithra over 6 years ago in reply to Richard Poley

Expert 1125 points

""use the shadow mode (TBCTL.PRDLD = 1) to ensure the timer & compare relationship is safely maintained"" , Can you please further explain this one.

Thank you

0 Richard Poley over 6 years ago in reply to Damith Pavithra

TI__Mastermind 27200 points

Sorry, that should be TBCTL.PRDLD = 0. Setting bit 3 of TBCTL to 0 enforces shadow updates on period register writes (p.339 of the TRM).

Regards,

Richard

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TMS320F28069M: About dynamically changing the ePWM control registers.