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msp430fr4133: capacitive differential measurement?

kazola
Guru 18635 points

Part Number: MSP430FR4133
Other Parts Discussed in Thread: MSP430FR4133, MSP430FR2633

Dear,

I have a one-pin capacitive measurement working for msp430fr4133 and free pins around ;)

However, instead of capacitance relative to ground, I would like to measure the capacitive change between two plates of a coplanar capacitor :)

This is "easy" with msp430fr2633 or fdc* IC but I would like to avoid them.

So, for this, should I simply substract the difference between two independent measurements?

I guess not so, which is your suggestion?

Have a nice day :)

  • 0
    TI__Guru**** 223817 points
    Hi kazola,

    So you are using Capacitive Touch I/Os with CAPSENSELIBRARY, which touch measurement method does your application support? Can you not drive one plate to ground as you measure the other electrode, or switch between driving electrodes while measuring relative to GND? Note that either method will not produce ideal results as this technology was not designed for this purpose. What variable creates the difference between the two plates that you are attempting to measure? You can experiment with different methods to find what produces a meaningful base count delta.

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Guru 18635 points

    Dear!

    I am using the "Pin Oscillator Method" but not CapSenseLibrary but I direct touch the registers. Ok! I will try your suggestions! :) The variable is some material between dthe plates.

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