3 Replies Latest reply on Sep 30, 2014 3:16 PM by user_14586677

    VDAC Voltage goes to maximum value while programming

    stefan.knobelspies

      Hi,

         

      While my PSoC5 is programmed with PSoC Creator the output of my VDAC component goes to the maximum value (in my case ~1V). Is there any chance to prevent this behaviour? Or is this a known problem?

         

      PS: The initial value is set to 0.25mV (Hex: 1).

         

      Kind regards,

         

      Stefan

        • 1. Re: VDAC Voltage goes to maximum value while programming
          user_14586677

          1) Is that because VDAC pin is HiZ as default ? And not terminated in any

             

          load that can absorb the leakage ?

             

           

             

          2) What is the concern over this pin developing a voltage ?

             

           

             

          Regard, Dana.

          • 2. Re: VDAC Voltage goes to maximum value while programming
            stefan.knobelspies

            2) The VDAC is connected to a transistor current source and i run into problems if i get the maximum current in my device while programming

               

            1) well i understand, but is there an possibility to change this?

            • 3. Re: VDAC Voltage goes to maximum value while programming
              user_14586677

              While programming the PSOC GPIO, not having been configured during

                 

              boot, must be Hi Z digital. I have to check on this. What is the schematic

                 

              look like for the external current source, are you seeing enough leakage

                 

              from a Hi Z pin to create the problem ?

                 

               

                 

              What is the range of current created by your external I source ? Maybe you

                 

              could use a GPIO to turn on its ground path once PSOC starts up ?

                 

               

                 

              From ap note AN72382 -

                 

               

                 

              www.cypress.com/

                 


                 

              Startup and Low-Power Behavior

                 


              Out of the box, all GPIO pins start up in an Analog  HI-Z
              state, where they  remain until reset is released.  The initial
              operating  configuration of each pin is loaded  during  boot
              and  takes  effect  at  that  time.  You  can  change  the  reset
              behavior  of  GPIOs  using  the  PRTxRDM  fields  of  the
              nonvolatile latch array, which are written when the PSoC
              is programmed.

                 

               

                 

              Regards, Dana.