5 Replies Latest reply on Nov 11, 2018 10:08 PM by xzng

    Difference count on MBR3116 does not return to 0 occasionally when object is removed from proximity sensor

    mikeb_3372801

      I'm bringing up a design that uses a single proximity loop (PS0) to detect if an object is present. The loop is a copper trace on top of a 4 layer PCB. I have followed all the design parameters and the proximity sensor appears to work well. I am able to detect objects reliably.

       

      The problem is that occasionally when an object has been left on top of the proximity loop for ~10-20 minutes and then removed the sensor button status stays "on". I can see via EZ-Click that the difference count is still saturated around ~300 counts.

       

      I have several boards and have noticed this at least three different times on three different PCBAs, so I believe this is a configuration setting or something with the algorithm internal to the PSoC.

       

      Could this be a function of the low pass filter? Is the chip auto-adjusting the baseline up since the object is present for a long while? Are there specific parameters I should be looking at adjusting to mitigate or stop this from happening?

       

      Any help is appreciated.