NAME

gpio — access gpio(4) pins from Lua

SYNOPSIS

local gpio = require 'gpio'

gpiodev = gpio.open(path)

pins = gpio.info(gpiodev)

gpio.close(gpiodev)

gpio.set(gpiodev, pin, flags)

gpio.unset(gpiodev, pin)

state = gpio.read(gpiodev, pin)

oldstate = gpio.write(gpiodev, pin, state)

gpio.toggle(gpiodev, pin)

gpio.attach(gpiodev, driver, offset, mask [, flags])

DESCRIPTION

The gpio Lua binding provides access to a gpio(4) device using the ioctl(2) interface.

gpiodev = gpio.open(path)

Open the gpio device and return an object to access its pins.

pins = gpio.info(gpiodev)

Returns the number of pins. As with all remaining functions, this can also be called using the : notation, i.e. as gpiodev:info().

gpio.close(gpiodev)

Close the gpio device.

gpio.set(gpiodev, pin, flags)

Set gpio pin flags. Note that the pin number in this and all remaining functions is zero based and not one based, this to avoid confusion with tools like gpioctl(8) which also number pins starting at zero. The following flags are defined:

gpio.PIN_INPUT

Pin is an input.

gpio.PIN_OUTPUT

Pin is an output.

gpio.PIN_INOUT

Pin is birectional.

gpio.PIN_OPENDRAIN

Pin is an open-drain output.

gpio.PIN_PUSHPULL

Pin is a push-pull output.

gpio.PIN_TRISTATE

Pin is tri-state (output disabled).

gpio.PIN_PULLUP

Pin has an internal pull-up enabled.

gpio.PIN_PULLDOWN

Pin has an internal pull-down enabled.

gpio.PIN_INVIN

Invert input.

gpio.PIN_INVOUT

Invert output.

gpio.PIN_USER

Pin accessible by users.

gpio.PIN_PULSATE

Pulsate pin at a hardware set frequency.

gpio.PIN_SET

Pin is set.

gpio.unset(gpiodev, pin)

Unset gpio pin.

stat = gpio.read(gpiodev, pin)

Read the current pin state.

oldstate = gpio.write(gpiodev, pin, state)

Write the pin state returning the old state. The following states are defined:

gpio.PIN_LOW

Pin is in the low state.

gpio.PIN_HIGH

Pin is in the high state.

gpio.toggle(gpiodev, pin)

Toggle pin state.

gpio.attach(gpiodev, driver, offset, mask [, flags])

Attach a device driver with offset, mask, and optional flags at a pin.

EXAMPLES

The following example code opens /dev/gpio0 and prints all pin values:

local gpio = require 'gpio' 
 
gpiodev = gpio.open('/dev/gpio0') 
 
local npins = gpiodev:info() 
 
for n = 1, npins do 
	print('pin ' .. n .. ': ' .. gpiodev:read(n - 1)) 
end

SEE ALSO

lua(1), luac(1), intro(3lua), gpio(4)

HISTORY

A gpio manual appeared in NetBSD 7.0.

AUTHORS

The gpio Lua binding was written by Marc Balmer <mbalmer@NetBSD.org>.