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MSP430FR2533: Rain drops cause false trigger

Kahsay Tsegay
Prodigy 10 points
Part Number: MSP430FR2533
Other Parts Discussed in Thread: TIDM-1021

We are using the part in an intercom product with a capacitve touch front. We are suffering from false trigger due to rain drops.

Apprecite for ideas how to optimize the driver/firmware without upgrading the layout (TX and RX re-routing)

  • 0
    TI__Guru 62491 points

    Hi Kahsay,

    There is a reference design, TIDM-1021 and document,  that describes why you are seeing false triggers and methods to mitigate them.

    Take a look and let me know if you need further guidance.

  • 0 in reply to Dennis Lehman
    Prodigy 10 points

    Hi Dennis,

    Maybe I was not clear with the "without upgrading the layout..". The product is on the market since a year ago and the issue reported eventgually. So we are in need of some kind of FW based solution. We cannont modify the HW of the product. 

  • 0 in reply to Kahsay Tsegay
    TI__Guru 62491 points

    Hi Kahsay,

    Ok - got it.  You probably need to check the touch thresholds and how your software handles the sensor processing in the callback.  

    Take a look at the TIDM-1021 software, in case you haven't seen it.  Scroll down about midway on the page and the download button is visible.

    Take a look at the function Keypad_Callback() in the reference code and the the algorithm described on page 19.  Do you do something similar to this in your callback?

    This algorithm made is possible to successfully pass the ""Degrees of Protection Provided By Enclosures (IP Code) IEC 60529".  You can find link to test passing in the TIDM-1021 document, section 3.2.4.

    To address this issue, you can try adjusting the touch thresholds a bit higher.  This is simple if you can connect the Captivate GUI to the target using the CAPT-PGMR, as you did during product development.  If you don't have any way to connect to the CAPT-PGMR, either using I2C or UART, then this becomes a challenge and will be a hit-or-miss process.

    What do you have for your conversion gain, conversion count values and touch threshold settings?

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