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LDC1614: Inductive Coil Matrix : eliminating crosstalk

Sreejit S
Prodigy 50 points
Part Number: LDC1614

Hello everyone.

I have made an inductive sensor array, similar to the 16-Button Keypad, (see the documentation TIDU954A) , the following figure is from the mentioned documentation.

The application requires several metal coins to be detected by each coil. The issue faced is the cross talk from other coils. When I select one coil via multiplexer and there are metal coins on other coils, the reading of the selected coil is affected by significant amount.

Is there a way to eliminate cross talks among the coil.

-Sreejit 

  • 0
    TI__Intellectual 2725 points

    Hi Sreejit,

    It seems like the coils are responding to conductive materials in the vicinity which is what they are supposed to do. Shouldn't you be able to adjust your detection threshold such that coins need to be directly on top of the coil for them to respond? Other things you can try are increasing the spacing between the coils and reducing the coil size.

    Regards,

    Varn

  • 0 in reply to Varn Khanna
    Prodigy 50 points

    Hi Varn,

    Yeah. I could change the detection threshold but the variation in values is just over a wide range which would mean that the threshold would have to be adjusted dynamically based on the number of coins in vicinity.

    -Sreejit

  • 0 in reply to Sreejit S
    TI__Intellectual 2725 points
    Hi Sreejit,

    I would propose, calculating a baseline which can be a moving average of the sensor readings and measure the shift above the baseline for each individual sensor. This will help you determine what thresholds you need to set for coin detection.

    Regards,

    Varn