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Original question:

MSP430FR2633: Clock selection for SPI interface using MSP430FR2633

MSP430FR2633: Use of capacitor at Rx Pin

Himani Bhatt
Intellectual 390 points
Part Number: MSP430FR2633

Hello, 

What happens if I keep capacitor across Tx instead of Rx? In terms of Capacitive touch buttons.

Will it damage controller MSP430FR2633?

Or will controller gets restart? Or Something else?

Any idea?

Thanks,

Regards,

Himani Bhatt

  • 0
    TI__Genius 17960 points

    Hi Himani,

    what do you mean by placing a capacitor across TX instead RX. When speaking in relation of capacitive sensing about TX/RX, it means your sensor capacitance is mainly between TX and RX. How can a capacitance be across one node? Please explain a bit more in detail, what kind of scenario you're considering.

    Many thanks in advance.

    Best regards

    Peter

  • 0 in reply to Peter Spevak
    Intellectual 390 points

    Hi Peter,

    Thanks for response,

    Am talking about EMI noise filter capacitor that we connect to RX pin, as described in "Capacitive Touch Design Flow for MSP430™ MCUs With

    CapTIvate™ Technology" pdf file.

    What will happen if I connect this capacitor to TX pin?

    The screenshot follows:

  • 0 in reply to Himani Bhatt
    TI__Genius 17960 points

    Hello Himany,

    understand your point. Well with mutual capacitance measurement approach, the TX pin is used to generate the electric field and trigger this way the charge transfer from TX to RX. As the RX pin is the sensing pin, and the TX pin is so to say the exciting pin, the application of the capacitor at TX will not address its purpose. On one hand, it will decrease the transferred charge to RX, thus the whole setup will tend to become less sensitive in terms of detecting touch events, which is not desired, and as the RX pin is the sensing pin and needs to be protected, the application at the TX pin will not address this protection purpose.

    Thus from multiple aspects the application at TX is useless and contra productive.

    Best regards

    Peter

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