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LAUNCHXL-F28069M: NEED information regarding how to use ePWM block

Li Chen92
Expert 3040 points
Part Number: LAUNCHXL-F28069M
Other Parts Discussed in Thread: C2000WARE

Hi TI expert

I have below questions, Could you please reply to this.

1. For the F28069M launchpad clock frequency is 90 MHz. So what is the maximum switching frequency we can use for generating PWM pulse? is there any limitation?

2.If I am generating any PWM pulse using some logic in Simulink can we directly apply the same PWM pulse to the EPWM block to generate the pulse and apply it to the hardware .is yes there please provide the process if no then pls mention the alternative process.

Best regards,

Thomas

  • 0
    TI__Mastermind 42195 points

    Thomas,

    1. The PWM is simply a counter. It counts to the value in TBPRD and then resets the counting logic depending on its configuration. The PWM counter is clocked by SYSCLK on this device, which is a  maximum of 90MHz. You can put 1 or 2 in TBPRD and it will cycle that quickly. You will need to choose an event that will toggle, set, or clear the PWM.  Being that you can't simultaneously turn the PWM on and off at the same time these events would need to occur on different clock cycles guaranteeing that you couldn't output more than 45MHz.
      1. Please note that the GPIO buffer his limitations too, these can be found in the Datasheet. Put more simply, the skew rate at 45MHz would be bad enough that it wouldn't look like a square wave. What switching frequency are you trying to hit? Go program it in the LaunchPad and see what the signal looks like. Use code from C2000Ware, or Simulink both will work.
    2. I suspect this depends on the format you have your logic in. So I would say this sounds like a great question for the Mathworks forum which support the Simulink tool.
      1. Here is a great FAQ on how to get Mathworks help. https://e2e.ti.com/support/microcontrollers/c2000/f/c2000-microcontrollers-forum/944441/faq-faq-support-for-using-mathworks-solutions-with-c2000-mcu-s 
      2. There are examples for the Device and PWM blocks, take a look here. https://www.mathworks.com/help/supportpkg/texasinstrumentsc2000/examples.html?s_tid=CRUX_topnav