Braswell GPIO Number correction

Discussion in 'UDOO X86' started by Quack, Aug 2, 2020.

  1. Quack

    Quack UDOOer

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    The pinout for the Braswell Gpio numbers in the documentation https://www.udoo.org/docs-x86II/ has 2 errors. It maps physical pin # 36 to GPIO 490 and pin # 37 to GPIO 492.

    The correct mapping is pin # 37 to GPIO 490 and pin # 36 to GPIO # 492.

    This is on X86II I haven't verified it on the X86.
     
  2. Quack

    Quack UDOOer

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    Is there any body there!
     
  3. Quack

    Quack UDOOer

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    Look it's easy to verify. Take a digital volt meter, attach it to ground and pin 36 . Then type:
    echo 492 | sudo tee /sys/class/gpio/export
    echo out | sudo tee /sys/class/gpio/direction

    Then toggle the output using:
    echo 0 sudo tee /sys/class/gpio/value
    echo 1 | sudo tee /sys/class/gpio/value

    Watch the volt meter.
     
    LDighera likes this.
  4. Quack

    Quack UDOOer

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    Correction, the 5th line should read :
    echo 0 | sudo tee /sys/class/gpio/value

    In the spirit of updating the documentation, there are 2 places in the docs which report Braswell pinouts. Under the Hardware & Accessories/GPIO/Braswell it lists 2 options after kernel 4.15 and before 4.15. As noted above the post 4.15 are essentially accurate.

    If however you click on Hardware Reference/Pinout Braswell, it just lists the pre-4.15 kernel #s.

    BTW the sysfs method of access shown above has been depreciated in favor of the libgpiod library. https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/. Iwill be posting more on that later in another thread.
     

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