3 Replies Latest reply on May 27, 2017 3:15 AM by user_418894472

    Maximum PWM clock speed for PSoC-5

    user_418894472

      Hi!

         

      Till date I have been programming PSoC-4 and the maximum PWM clock speed is limited to half of  system clock. i,e, 48/2 = 24MHz.

         

      Now I am wanting to try out PSoC-5. I just built a project with a PWM block feeding from a 78MHz clock. It compiled without errors.

         

      Another thing I don't understand is that even when I change the clock speed to say 500MHz, there is no error but only a warning that the clock speed is outside tolerance.

         

      I also 'loosely'  recall that even for PSOC-5 the maximum PWM speed is half of the system clock speed.

         

      My question is: What is the maximum permitted speed for PWM in PSOC-5?

         

      Thanks

        • 1. Re: Maximum PWM clock speed for PSoC-5
          user_365962704

          Are you talking about feeding the clock input on the PWM component? At the end of the PWM Datasheet is the AC specifications, if i remember correctly (i have not the datasheet at hand) the max. clock frequency at the clock input of the PWM component is around 64MHz, you can put more but the behavior is not stable.

             

          If you are talking about the max. frequency the PWM component can generate is ~24MHz (limited by the max frequency the GPIOs can handle).

             

           

             

          Hope it helps, check the PWM datasheet at the end is the table with some information not available on the first pages.

             

          Carlos

          • 2. Re: Maximum PWM clock speed for PSoC-5
            user_418894472

            Thanks for the quick response. I didn't know that the GPIOs were limited to 24MHz

               

            Anyway I dont really want the output to change as fast as 24MHz. It's just the clock speed I was talking about.

               

            Thanks

            • 3. Re: Maximum PWM clock speed for PSoC-5
              user_418894472

              I have set my PLL frequency to 64MHz and I am using a 78MHz clock for the PWM.

                 

              It compiles correctly without errors. Why am I not getting an error when the clock frequency of the PWM is greater than the PLL frequency?