PSoC 4 CapSense Sensor Auto-Reset – KBA222882

Version 2

    Version: **

     

    Translation - Japanese: PSoC4 CapSense 自動リセット- KBA222882 - Community Translated (JA)

     

    Question:

    How does PSoC® 4 CapSense® sensor auto-reset work?

     

    Answer:

    When a filtered raw count is calculated from noise filters, there are three cases for baseline update:

    • Case 1: The filtered raw count is lower than the negative noise threshold. In this case, the device executes the low baseline reset process. The baseline is not updated.
    • Case 2: The filtered raw count is in within the positive and negative noise threshold range. In this case, the device executes the baseline update process. The process is shown in Fig-1.
    • Case 3: The filtered raw count is higher than the positive noise threshold. In this case, if ‘Sensor auto reset’ is disabled, the baseline is not updated; if sensor auto-reset is enabled, the device executes the baseline update process. The process is shown in Fig-1.

     

    Untitled.pngFig-1

    Enabling sensor auto-reset limits the maximum duration for which the sensor stays ON (typically 5 to 10 seconds). This setting prevents the sensors from permanently turning ON when the raw count accidentally rises because of a large power supply voltage fluctuation, or a sudden change in noise conditions. Use this setting to avoid latch-up of sensors in high-noise conditions. In some cases, if you want to stretch the maximum time duration for sensor staying ON with sensor auto-reset enabled, modify the size of Baseline_Update_Buffer (default size is 8-bit). Contact Cypress sales or technical support for more information.

    Reference:

    PSoC® 4 and PSoC Analog Coprocessor CapSense® Design Guide

    PSoC 4 Capacitive Sensing (CapSense®) Datasheet