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Thread: AnalogRead floating problem

  1. #1
    Junior Member
    Join Date
    Nov 2018
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    5

    AnalogRead floating problem

    Hey guys,

    So I have my reading and this input generated from: tip touching(or almost touching) a conductive sample --> tiny current going through amplifier --> goes to teensy

    the whole circuit & teensy powered by external 3.3V. As known that there is floating voltage problem, but 1.I cannot solve it by conducting to the ground because I need to read that input. 2.I cannot solve it by adding resistor because I think it will filter out my tiny current ( the floating is random reading between 900~2000, current i want to read around 1200~1400 and it kind of satbilize in a range of 100 to each other)

    the reason why this is a problem to me right now is because i need to add a motor that level down the tip to the sample, i was hoping the pin could read nothing/something tiny, and when I approach my tip to the sample, the current kind of tunnel through the tip and goes to the teensy, and the motor will automatically stop

    If anyone has any idea to help, that would be great and I will really appreciate it

    Thanks!

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    7,077
    Try using :: int touchRead(uint8_t pin)

    for ref :: In file ...\hardware\teensy\avr\cores\teensy3\touch.c

    It will return some stable low value … perhaps ~500 to 1000, and will go higher on touch presence.

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