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Built-in LED of 13th pin would affect to other signal output from the same pin?

Discussion in 'Arduino' started by Willen, Mar 21, 2017.

  1. Willen

    Willen Well-Known Member

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    Talking about Arduino UNO, some UNO has built-in LED (L LED permanently connected to 13th pin) in the board and dafault 'blink' program use it to blink the LED. But during other projects, many programs uses same 13th pin for other type of signal out. In this time, the signal has a 1k and a LED always in parallel. Won't the parallel LED affact different types of signal comming out from the 13th pin?

    (Additional: Some Chinese clone (CH34) UNOs has no such L LED, just has empty pads on boards.)
     
  2. fezder

    fezder Well-Known Member

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  3. fezder

    fezder Well-Known Member

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    Or go crazy and bit-bang SPI if hardware SPI gives trouble :p
     
  4. dave

    Dave New Member

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  5. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    The driver inside the processor chip can source about 25mA, and sink about 40mA. The LED current limiting resistor is set up to drive the LED with about 5mA, so it slightly decreases the ability of the Arduino's pin 13 to source current while slightly increasing its ability to sink current.

    Bottom line, you can treat it like any other pin...with or without the LED.
     
    Last edited: Apr 17, 2017
    • Agree Agree x 1

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