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MSP430G2755: Pin required by RO and Resistor based Capacitive touch on MSP430G2xx

Alberto Soattin
Genius 16905 points
Part Number: MSP430G2755

Hi Support,

referring to our SLAA363A, can you kindly confirm me how many GPIOs are required to implement 3 capacitive keys with both RO method and Resistor Based method?

Is it possible to receive PCB recommendations for Capacitive Keys implementation? In particular two questions:

  1. Is it mandatory to have solder protecting sensible area? 
  2. Bottom ground plane and Top guard plane need to be connected or do they need to be "independent"? If yes, is it correct to connect to ground the Bottom one?

Thanks and regards,

Alberto

  • 0
    TI__Guru**** 204617 points
    Hi Alberto,

    As you can see from SLAA490 & SLAA491, the MSP430G2xx5 supports PINOSC modes which requires only one GPIO per capacitive sensor. Relaxed oscillation is the superior capacitive sensing technology compared to resistor-based and should be used since the PINOSC function is available. Please refer to the RO_PINOSC_TA0_WDTp_Wheel_Buttons example.

    A Capacitive Touch Hardware Design Guide is provided in SLAA576. A solder mask is required to insulate between the capacitive sensor plate and the user's finger. The guard and ground planes should be connected.

    Regards,
    Ryan

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