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.
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.
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.
