Gpio

The Gpio API provides high level access to GPIO pins through the Linux /sys/class/gpio interface.

Basics

Invoke Gpio.open to open a given GPIO pin number and direction. Use read and write to read and toggle the pin value:

g := Gpio.open(18, "out")
g.write(1)
g.read
g.close

Once you are finished with a pin, call close to free the backing native process.

Listening for Changes

To monitor changes to a GPIO pin output, you can use Gpio.listen. This method will register an interrupt handler that triggers on the rising, falling, or both edges and efficiently poll for pin state changes:

g := Gpio.open(18, "in")
i := 0

g.listen("falling", null) |val|
{
  echo("Pin is now $val")
  if (++i == 5) g.close
}

echo("Pin was read 5 times")

To receive a callback after a period of time has elpased (regardless if pin state has changed), pass in a duration to Gpio.listen:

g.listen("rising", 5sec) |val|
{
  ...
}