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TMS320F28375S: Generating a quadrature pulse output

Lauren Mayfield
Expert 8175 points

Part Number: TMS320F28375S

Hi team,

My customer is using the TMS320F28375S. Their product must generate a quadrature pulse output that varies over time based on a particular transfer function in the firmware. What is the best way to generate a quadrature pulse stream by using the ePWM timer hardware? Should they use one ePWM channel with A and B, or two independent ePWM channels? Can two independent ePWM channels be synchronized?  

Thanks,

Lauren

  • 0
    TI__Genius 15385 points

    Hi Lauren,

    I have forwarded this post to our EPWM expert, he should get back to you soon.

    Best Regards,

    Nirav

  • 0
    TI__Guru 52220 points
    Lauren Mayfield said:
    Can two independent ePWM channels be synchronized? 

    Yes they can be.

    Lauren Mayfield said:
    use one ePWM channel with A and B, or two independent ePWM channels

    Either way would work you have to look at what you are trying to implement. If you use one EPWM and want to implement a phase shift between A and B output, you put the phase shift in the CMPA vs CMPB values. You would do all of the calculation yourself. So it makes it a bit more complicated. However if you want to use deadband, as in A and B are complementary, then the one EPWM module solution would be simpler.

    It always depends on what type of output signal you are trying to generate.

    Nima

  • 0 in reply to Nima Eskandari
    TI__Expert 8175 points

    Hi Nima,

    Thank you for your help!

    Will the deadband be able to create a 90 degree phase shift?  Complementary output tend to be equal and opposite with the deadband time being very small.  It seems like using two sequential A channel ePWM’s is probably the best way to go for the most flexibility.  Do you agree?

  • 0 in reply to Lauren Mayfield
    TI__Guru 52220 points

    You can definitely invert your EPWM signal in the deadband module. In general duet to the phase shift requirement, I would go with the two A channels.

    Nima