PWM interrupts (or, how I learned to stop worrying and love the PLIC)

I’ve used the PWM peripheral for generating external facing signals but now I want to use the PWM as a fast interrupt source. I’ve setup the PLIC to generate an external interrupt using the PWM module as the source, as in this quick and dirty example:

HiFive1 PWM interrupt sample

It should be setting a global variable which, when set, will be tested in the main loop and invert the green LED (embedded for “Hello, world!”). However, that never happens? If I put in a puts() statement within handle_m_ext_interrupt() I see that the interrupt is firing as expected.

In contrast, if I setup an internal timer interrupt the same logic works as expected:

HiFive1 Timer interrupt sample

I’m sure I’m missing something obvious about using external interrupt sources that was probably stated numerous times in documentation, but I can’t quite put my finger on it.



Nevermind. I was mistaken and it’s working fine. :blush:

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Great! Thanks for the examples!

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