5 Replies Latest reply on Oct 15, 2012 12:37 AM by rajendra.prasad

    PrISM_Example Project

    rajendra.prasad

       Hi to all,

         

                    can we blink 2 LEDs with a frequency of 500 hz , can anybody suggest with the modifications to run at that frequency.

         

       

         

      Thanks

         

      Rajendra

        • 1. Re: PrISM_Example Project
          ki.leung

           The PrISM can control 2 LEDs aready.

             

          What do you mean by 500hz? if you wan tto use 500 hz clock, you just change the 20khz clock to 500hz, but I think the result would not be good as you would see flicking.

          • 2. Re: PrISM_Example Project
            user_14586677

            If your task is to turn two leds on and off at a 500 Hz rate, and no other features needed, like dimming,

               

            then simply use a timer configured for 500 Hz and drive the leds via two digital pins.

               

             

               

            Is that a description of what you want to accomplish ?

               

             

               

            Regards, Dana.

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            • 3. Re: PrISM_Example Project
              rajendra.prasad

              yes i want that only Sir

                 

               Thank u sir

              • 4. Re: PrISM_Example Project
                user_14586677

                Simplist woukld be -

                   

                 

                   

                1) Place a clock onto schematic, double click it, select "new", set freq to 500 Hz, source to "auto"

                   

                2) Place 1 or two digital output pins onto schematic, wire them to clock.

                   

                3) Double click each pin, set to "strong", slew rate to "slow", Current to "4 mA source, 25 mA sink"

                   

                 

                   

                You are done. If you want to save a pin, and are using 5V as Vdd, you could connect both pins to Vdd

                   

                in series, and a series resistor, to limit current. R = Vledonmax/25 mA. If you are using 3.3 Vdd LED

                   

                threshold max probably too high so that means 1 led/pin.

                   

                 

                   

                Note LEDs are driven from low side, so pin set to 0 turns them on.

                   

                 

                   

                Regards, Dana.

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                • 5. Re: PrISM_Example Project
                  ki.leung

                  Are you sure you want to drive LED with a 500hz? You can see the signal with a CRO but may not see it blink as it is too fast for you eye.

                     

                  I think you want to use 500hz to drive the PrISM, but again this would make the switching speed to slow (dvided by 256 with the counter inside the PrIsm)  Best to read the spec. of PrISM again.

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                  • 6. Re: PrISM_Example Project
                    rajendra.prasad

                     i got it.

                       

                    thank u