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MSP-EXP430FR6989: ESI LC sensor sensitivity

user3756035
Prodigy 30 points

Part Number: MSP-EXP430FR6989
Other Parts Discussed in Thread: TIDM-LC-WATERMTR, TIDM-INDUCTIVEPROX

Hello,

I am trying to make an inductive sensing of a water meter spinning wheel. 

So far I tried example TIDM-INDUCTIVEPROX, which is using only one sensor. The detection with this SW was very good, how ever I need two LC sensors. So run the example TIDM-LC-WATERMTR with two LC sensor, it somehow works (not very reliable) but I can't get the sensitivity to metal as was in the example with only one sensor. I am using the same combination of C and L. I was changing the values of separation factor and distance, however the sensitivy still isn't as good as in the example with one sensor.

What else can I do to increase the sensitivity? Or should I just modify the first example to 2 LC sensors?

Thank you  

  • 0
    TI__Mastermind 46765 points

    Hi,

    Based on your description, you are using PCB coil as the inductors in the TIDM-LC-WATERMTR. The PCB coil can create a stronger electromagnetic field than the regular one. However when you have two PCB coils on your board, especially when you placed closely, they will influence each other reducing the strength of the electromagnetic field. So the sensitivity is getting down.

    Use the regular inductors like the one in TIDM-LC-WATERMTR. Although the sensing distance is shorter than PCB coil in TIDM-INDUCTIVEPROX. But with a proper setting, you can get up to 10mm sensing distance.

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Prodigy 30 points

    HI, 

    Thank you for your answer!

    I am using the same lc sensor made from regular inductors in both examples, in the  TIDM-INDUCTIVEPROX of course just the half of it. 

    Could the interference between the two inductors so high that it lowers the sensitivity so much?

    With best regards,

    Miroslav Slavik

  • 0 in reply to user3756035
    TI__Mastermind 46765 points

    Hi Slavik,

    Sorry for the late response. The PCB coil is detecting if there is metal around it and affecting the oscillation. Another PCB coil placed around it is just like place a metal around it. So the effect is obvious.

    Best regards,

    Cash Hao

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