2 Replies Latest reply on Apr 10, 2019 3:28 PM by skguc_4116786

    CY8C9540 resetting from toggled input


      I have an issue I am trying to track down and am wondering if anyone here has any insight.  The entire chip (CY8C9540) crashes/resets when toggling certain input pins (P1_B6 and P1_B7).  Every pin on that port is configured the same (pulled up) and are also used as inputs, but these two will periodically (roughly 50% of the time) reset the entire chip when pulled low.  The other inputs work fine and as expected.  The only thing I can think of is maybe the problem is related to these pins also sharing I2C address functionality, but pin A0 is pulled hard to ground, so they should be out of that picture.  Has anyone else ran into this issue of have any ideas for me to try?  Thanks.

        • 1. Re: CY8C9540 resetting from toggled input

          Looks "not responding to I2C" is the only software reset source besides the Hardware reset source(POR and XRES), I think worth checking again the I2C addressing configurations in your design. Also, check the sch/layout of your circuit board make sure there is no hardware wiring issues.

          Hope you are using CY8C9540A, which is a new version of CY8C9540 (no "A").

          Use OSC to probing the funcational pins of the device when togglling the P1_B6 and P1_B7 pins would be helpful to debug the issue.

          • 2. Re: CY8C9540 resetting from toggled input

            Scoping the lines helped diagnose the issue.  It turned out that the debounce circuit was the culprit.  It was imparting too negative of a voltage for too long on those pins.  On other pins, it was fine for some reason though.  Removing the debounce capacitors and/or adding a series resistor to the input switch (reed style float sensor) fixed the problem.