Chiliboard/Using GPIO and LED

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Using GPIOs and LEDs

Chiliboard has two built-in user LED's, and a lot of unused pins that can be used as general-purpose input/output lines (GPIO).

User LED's

User leds can be controlled by /sys/class/leds directory, and are visible as led0 and led1 subdirectories. By default led0 uses heartbeat trigger. To turn on the led1, type:

echo 1 > /sys/class/leds/led1/brightness

and to turn off

echo 0 > /sys/class/leds/led1/brightness


GPIO lines can be controlled from the user space via the directory /sys/class/gpio.

For example, to set the GPIO1_8 pin to 1 do:

  • Calculate the index of the pin as 1*32+8 = 40 and export it to the gpio subsystem using:
echo 40 > /sys/class/gpio/export
In the /sys/class/gpio will be created gpio40 directory representing selected pin.
  • Set the direction of the line:
echo out > /sys/class/gpio/gpio40/direction
  • Then the value of the line
echo 1 > /sys/class/gpio/gpio40/value