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Thread: Teensy++, three pins won't go low

  1. #1
    Junior Member
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    Teensy++, three pins won't go low

    Hi,

    I wanna use the pins called 38-45 (F0-7) on this PDF:
    https://www.pjrc.com/teensy/card4b.pdf
    as digital output.

    pinMode(38, OUTPUT);

    and then a simple digitalWrite(38, ... HIGH/LOW blinker works just fine.
    38, 39, 40 and 41 all good but 42, 43, 44 and 45 won't go low. They even stay HIGH when I set them as inputs.

    Teensy is not connected to anything else.

    Is there anything special withe these three pins?
    Last edited by frax; 11-25-2020 at 07:02 PM.

  2. #2
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    Found this which seems to be identical:
    https://forum.pjrc.com/threads/56227...-control-PORTF

    Could this be a clone? Bought it years ago, don't remeber where. But I have one more Teensy++ which Im sure is not a fake, i'll give that one a try.

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Is it a genuine Teensy++ 2.0, or maybe a counterfeit? Can you show us a photo of the board?

  4. #4
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    And the suggested
    MCUCR = (1<<JTD) | (1<<IVCE) | (0<<PUD);
    MCUCR = (1<<JTD) | (0<<IVSEL) | (0<<IVCE) | (0<<PUD);

    works perfect, all pins behave as expected now

  5. #5
    Junior Member
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    Here's a picture of the apparently fake Teensy.

    Click image for larger version. 

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  6. #6
    Senior Member PaulStoffregen's Avatar
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    Yup, that's definitely a counterfeit.

    If you bought it within the last 90 days, odds are good you'll get your money back with a complaint.

  7. #7
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    Bought it years ago, probably of ebay.

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