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TMS320F28376S: Discrepancy in PWM Frequency within the F2837xD and F28376S

Part Number: TMS320F28376S


Hello, 

On the Launchpad, we have been managing very easily to generate 200kHz waveforms in the PWM module. We have designed our own board, but could only get the single core version in stock - but it is suffice for our requirements. 

However, when migrating the code over from the dual core version to the single core version, I have noticed that I need to half my TBPRD value in the PWM registers to enable the same PWM frequency, despite not a single other thing changing within the code.

I can't seem to find the answer online, but my assumption is that the maximum EPMW time-base clock is 50MHz for the F28376s, not 100MHz like it is in the F2837xD devices. 

Can someone confirm the above, or give other advice? We are using a clock divider of 1 and the high-speed clock divider also at 1. This worked on the Launchpad at 200kHz, but PWM output was 100kHz in the single core version.

Looking forward to the response.

Best regards,

JMH

  • Hi JMH,

    These should be the same frequencies (SYSCLKOUT=200MHz, EPWMCLK=100MHz). Could you please double check what your EPWMCLKDIV is set correctly? I ask because this defaults to SYSCLKOUT/2.

    Is the code you are running on each device the same? Or are you changing anything when you switch over? Another thing to check is count mode (up-count vs up-down count) - if they are different that would result in different frequencies and needing to half your TBPRD.

    Let me know if you can confirm these!

    Best Regards,

    Allison