Modifying TI C2000 ePWM block output

Question

Mike Buba 2022-9-17

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https://ww2.mathworks.cn/matlabcentral/answers/1807170-modifying-ti-c2000-epwm-block-output

回答： Samar 2025-4-25

Is it is possible to modify an ePWM output to do additional calculations before sending a PWM signal to GPIOs.

For example, I would one of the switches to switch using the following logic:

or

For the first three signals am sending a reference to a PWM block, but my fourth PWM signal is calculated as a combination of the first three PWM signals, i.e. forth signals does not have a reference.

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Omar Shouman 2022-10-25

Hello Mike,

I want to do the same thing. I was wondering if you were able to do it or find an alternative. That would be very helpful.

Thank you for your time.

Kind Regards,

Omar

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Answer 1

Samar 2025-4-25

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https://ww2.mathworks.cn/matlabcentral/answers/1807170-modifying-ti-c2000-epwm-block-output#answer_1564244

Hello @Mike Buba, @Omar Shouman

As per my understanding, you are trying to implement a custom logic for ePWM4. You are trying to derive the output of the fourth ePWM as a logical combination of the other three ePWMs.

This is possible, the following steps should be followed to implement this logic:

Use “ePWM” blocks to generate the first three PWM signals with the usual workflow.
To know the logical state of a digital pin, use the “Digital Input” block. Connect one block to each of the GPIO pins. Make sure the sample time is same for corresponding ePWM and Digital input block.
For the above function you can also use “From Workspace”.
To apply logical operation, use the “Logical Operator” block. Select the desired logical operation and feed the three ePWM signals to it.
The output from this logical operator block is the desired ePWM4. Since this is not from a reference signal, there is no requirement of using another ePWM block. Instead, we can directly connect this output to drive a “Digital Output” block.

There are some points to be noted:

Make sure that the PWM frequency of the three base signals is sufficient for the logic to make sense at GPIO level.
The sample rate of the logical operation block should be high enough to capture all the transitions.

Refer the screenshot given below to understand the step-by-step procedure mentioned above. Here I have tried to create 4th ePWM by taking XOR operation of the existing three ePWMs.