4 Replies Latest reply on Mar 6, 2013 2:15 PM by user_14586677

    ISR module

    user_200706552

       Hi all

         

      Please info how max clock speed ISR module ?

         

      Im testing interrupt with ISR module with Clock module and maximal frequency is aprox. 3-4 kHz. How to use ISR with bigger frequency ?

         

      Thanks Info

         

       

         

      Kamil

        • 1. Re: ISR module
          user_1377889

          The max frequency of interrupts in psoc5 depends mainly what you actually do within the ISR.

             

          The TRM for PSoC5  (Pg. 50) says that at least 12 cycles latency is needed to enter the ISR, every Instruction will need some cycles too, so much for the frequency.

             

          Usually developers are intrested on the reaction-time on a signal, not on max frequency. So I'd like to ask what you want to perform with a high interrupt rate.

             

           

             

          Bob

          • 2. Re: ISR module
            user_200706552

             My idea is audio buffer operation - like filter, shaper, delay, multiply .....

            • 3. Re: ISR module
              user_1377889

              I would suggest to use something like ADC, DFB (Digital Filter) and the use of DMA to transfer information from one block to the other. That will not use any CPU and runs as fast as the ADC will. 

              • 4. Re: ISR module
                user_14586677

                As bob mentioned DMA a good choice in case of filter, which also

                   

                can be used for delay, eg. allpass etc...becuse this can all be HW

                   

                processed.

                   

                 

                   

                But if you have to do processing the filter cannot handle, ISR effectiveness is

                   

                best when you do nothing more than set a flag in ISR and exit. That way, by

                   

                not calling any f()'s within ISR you dont get a lot of stack push, hence MIPs

                   

                wasted. It's generally a good practice to handle ISR response this way.

                   

                 

                   

                Regards, Dana.