Forum Discussion

JYang101's avatar
JYang101
Icon for New Contributor rankNew Contributor
6 years ago
Solved

PWM control problem

Hello guys. I'm designing a circuit of sort,and the part of PWM is having issue,don't know why... So I'll briefly describe my PWM specs; a 4-bit Input named Value, Input clock 50MHz, a single bi...
  • a_x_h_75's avatar
    a_x_h_75
    6 years ago

    Where is your test code? That is where control of 'value' comes from. Or did Quartus create that for you? Is that why you can't find where to change it?

    I recommend that you use ModelSim - a much more widely use simulation tool. Look at this guide:

    https://www.youtube.com/watch?v=qZNL1C0TwY8

    The example is similar to the code you're using. Get the test bench right and I think your code will do what you want.

    Cheers,

    Alex

a_x_h_75's avatar
a_x_h_75
Icon for Contributor rankContributor
6 years ago

It looks approximately right to me. Try changing your 'value' less frequently - every 6 clock cycles (or so) is far too quick. You'd usually expect to set a desired PWM value for multiple PWM cycles (16 clocks per cycle in your case) before changing it.

There are certainly some more elegant ways to code this. However, as I've said your code should do something approximately right. So, modify as above and confirm whether it behaves as you'd expect.

Cheers,

Alex

  • JYang101's avatar
    JYang101
    Icon for New Contributor rankNew Contributor
    6 years ago

    First,thank you for reply.

    Where I stuck is exactly don't know how to make `value` to slower,I can't figure out how to make a `input` to change slower to 16 clocks...

    Can you give me some ideas?any hint?I've already tried lots ways,but it all end up the same,the PWM has its output but due to `value` changing too fast...it just don't make it right.

    What I'm trying to achieve...