user led / prototyping header

[romang]

Hello. I wonder if there any code examples on how to put output on external pins from application on aroid os. Or if there any example on how to use user led on the board (GPIO_142 pin on the processor).

[~fgiff]

As with non-android Linux, you can manipulate GPIOs from userspace using sysfs, though you almost certainly will need root privileges to do so.

To toggle USR_LED for example, you can use the following commands from the serial console:

echo 142 > /sys/class/gpio/export # Export GPIO142 (USR_LED on schematic) to userspace
echo out > /sys/class/gpio/gpio142 # Set GPIO142 as an output
echo 1 > /sys/class/gpio/gpio142/value # Set GPIO142 ON (turn on USR_LED)
echo 0 > /sys/class/gpio/gpio142/value # Set GPIO142 OFF (turn off USR_LED)