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Thread: pins for the teensy3.6 and teensy4.0/1 Data Command alternatives

  1. #1
    Senior Member
    Join Date
    Sep 2016

    pins for the teensy3.6 and teensy4.0/1 Data Command alternatives

    Hello engineers,

    could someone tell me which alternative pins can be used for the Data/Command lines?

    I tried in my previous MAX31855 post pin 9 and pin 10, swapped them and the display still freezes over.

    is there an alternative pin to this DC pin?

    thanks for your help and reading.


  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Flagged other duplicate post back to here ...

    DC should work as any digital pin not otherwise used.

    More info would be needed about display and connections overall - and some code perhaps - to understand what could be the trouble. Both are SPI devices ? - perhaps pullups are needed or the display doesn't tristate the SPI pins

  3. #3
    Senior Member
    Join Date
    Sep 2016
    Hi Defragster:

    I did the following:

    continued testing at the advice of Kurt.

    removed the DigitalWrite commands in the void loop, because adafruit max31855 does it automatically, the HX8357_t3n also.

    all MAX31855 and Featherwing 3.5 inch is hooked up with a Pull up to 4.7K and MISO is hooked up to a 10K voltage divider.

    I didnt build in a tristate, i dont have one. still all is tested and the signal floats if the SPI to 1.795 V if MISO channel is not used.
    Last edited by Bastiaan; 09-18-2020 at 09:05 AM.

  4. #4
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Again need to localize down your issue.

    Note: HX... display by Adafruit - Does not need MISO pin as the device is read only... Unless you are using something like the SD card on the display.

    DC - Depends on which Teensy? With T4.x can be any pin, with T3.x may need to be Hardware CS pin. Don't remember if we made that required or only highly suggested in this case as it does speed things up.

    Sorry I have no idea what the 10K voltage divider does for the MISO pin.

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