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MSP430FR2633: CapTIvate proximity measurement accuracy

Munan Xu
Expert 5110 points
Part Number: MSP430FR2633


Hello,

I have a customer who is trying to measure distance in a proximity sensing application.

I see we have some tests measuring detection range:

http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/CapTIvate_Design_Center/latest/exports/docs/users_guide/html/CapTIvate_Technology_Guide_html/markdown/ch_design_guide.html#proximity-range-test

Is there also some data on the range measurement accuracy we can expect in a "best case" scenario such as in the tests above?

The goal would be to get about 0.5 cm measurement accuracy for an object such as a hand.

Regards,

Munan

  • 0
    TI__Guru 71216 points
    Hi Munan,

    We don't have any additional data for proximity measurements. The purpose of these tests is to demonstrate approximate proximity distances based on the electrode design and surrounding ground planes.

    You indicate your customer needs 0.5cm accuracy. Do you mean a hand is detected when placed only 0.5cm away from the sensor? Or do you mean a hand can be detected, within 0.5cm accuracy, at any distance from the sensor?
  • 0 in reply to Dennis Lehman
    TI__Expert 5110 points
    Hello Dennis,

    The capacitive sensor should detect a hand up to a distance of 10 cm away, and closer.

    There is an “ideal” range of 2-6cm and so the goal would be able to determine whether the hand was in the ideal range to an accuracy of 0.5 cm. Is this an accuracy that can be reasonably achieved with some tuning?

    Regards,

    Munan
  • 0 in reply to Munan Xu
    TI__Guru 71216 points
    Hi Munan,

    Our experience with other customers is 10 cm is out of the range of reliable detection for almost any application. The reason is the sensitivity can be dramatically affected by the surface area of the electrode, layout, surrounding grounds, power planes, and other nearby conductive objects. We have found that 2-3cm is probably the most realistic range, and again it depends on all the parameters described above. Within the 2-3 cm range and accuracy of 0.5cm is certainly possible.

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