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Thread: Inverting pin signal for bi-color led

  1. #1
    Junior Member
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    Inverting pin signal for bi-color led

    I'm sure this is documented somewhere, but I can't find it...

    Looking at picking up a bi-color led like this:

    https://www.mouser.com/ds/2/26/Apem_...Q6-1158530.pdf

    The color is changed by reversing the polarity of the supply voltage.

    Clueless as to how to implement this. AnalogWrite() does not accept negative value, AFAIK.

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    With a 150R current limiter resistor between 2 GPIO pins. Drive one high, the second low (always with digitalWrite()) = one color. Drive the first low, the second high = other color. Both high or both low = LED off.

  3. #3
    Senior Member+ Theremingenieur's Avatar
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    It was documented in the electronics class in secondary school...

  4. #4
    Senior Member Wozzy's Avatar
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    You can also use the method described in THIS POST to drive your Bicolor LED, from only a single pin.
    This can give you Red Green or Yellow.

    EDIT: Actually, Never Mind... this won't work because you can't tie in between the two LEDs on a two pin device.
    Theremingenieur's method is the way to go. Note that you can also get yellow by toggling between the two states very rapidly.

  5. #5
    Junior Member
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    thanks for your response.

    Must stop nodding off in class....

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