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IR sensors ADC and multiplexing

Discussion in 'Microcontrollers, Programming and IoT' started by shadab, Oct 3, 2011.

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  1. shadab


    Oct 3, 2011
    hello every1,

    i am working on making a type of a slate using IR lights n sensors..
    now what i basically want to do is have IR leds to plot X and Y axis and IR sensors onthe opposite ends to recieve the singals. when i place my finger in between a sensor fails to get the IR signal. now my board is supposed to have 10X10 sensors.... so i want to be able to know which sensor didnt get the IR signal....

    plz help me with the process of how i make the connections and supply the digital data to any microcontroller....
    thanx... :)
  2. OLIVE2222


    Oct 2, 2011
    I doubt that the beam from an IR led will be narrow enought to allow correct detection. Probably many detectors will show the beam even with a finger between.
    Do you already try a basic single led+sensor barrier before going further?
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    This technique was used on the "touchscreen" of the HP150 computer.

    There were 20 (from memory -- could have been 21) beams vertically and some smaller number horizontally It could provide resolution to line and pair of characters on the screen.

    Both the emitters and the detectors were recessed to shield them somewhat from adjacent beams.
    Last edited: Oct 14, 2011
  4. eptheta


    Dec 20, 2009
    Wow, that is cool. I'm pretty sure that if you bury the IR sensors in a deep, non reflective hole with a narrow opening, they'd only be able to pick up IR from LEDs directly opposite it, but I guess you'll just have to experiment.

    The interfacing should be pretty easy. You probably have more than 20 IO ports on your uC, so just hook them up and check the pins at a decent frequency.
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