2 Replies Latest reply on Sep 6, 2014 4:36 AM by DaKn_263916

    Strange timing on pin writes


       I'm seeing some strange behaviour writing to pins on a PSoC 5LP.  I'm writing a 6-bit value to six pins grouped as a bus.  I'm then writing a 1 followed by a 0 to a separate pin.  The changes on some of the bits within the bus don't always happen concurrently.  In fact, some of them occur *after* the strobe is cycled.


      Here's the code I'm using:




      Here's what the resulting timing looks like.  Anyone know what's going on?

        • 1. Re: Strange timing on pin writes

          It is a bit difficult to judge from a picture what the cause of the strange behavior is. Can you post your complete project, so that we all can have a look at all of your settings? To do so, use
          Creator->File->Create Workspace Bundle (minimal)
          and attach the resulting file (do NOT use chrome, that still may not work).





          • 2. Re: Strange timing on pin writes

            First the Saleae logic analyzer way too slow to get accurate timing.


            Although display you show is relatively (within 135 nS) correct.




            Consider a scope and look at the trigger vs a specific channel. In fact


            you can trigger DSO on a pin changing before strobe as a condition.


            Or on a condition of excessive delay of a pins response.




            What is used as the trigger, the STB ?




            Regards, Dana.