.\"	$NetBSD: gpio.3lua,v 1.4 2014/01/07 21:54:17 mbalmer Exp $
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.\" Copyright (c) 2013, 2014 Marc Balmer <mbalmer@NetBSD.org>.
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.Dd Januar 7, 2014
.Dt GPIO 3lua
.Os
.Sh NAME
.Nm gpio
.Nd access
.Xr gpio 4
pins from Lua
.Sh SYNOPSIS
.Cd "local gpio = require 'gpio'"
.Pp
.Bl -tag -width XXXX -compact
.It Dv gpiodev = gpio.open(path)
.It Dv pins = gpio.info(gpiodev)
.It Dv gpio.close(gpiodev)
.It Dv gpio.set(gpiodev, pin, flags)
.It Dv gpio.unset(gpiodev, pin)
.It Dv state = gpio.read(gpiodev, pin)
.It Dv oldstate = gpio.write(gpiodev, pin, state)
.It Dv gpio.toggle(gpiodev, pin)
.It Dv gpio.attach(gpiodev, driver, offset, mask [, flags])
.El
.Sh DESCRIPTION
The
.Nm
Lua binding provides access to a
.Xr gpio 4
device using the
.Xr ioctl 2
interface.
.Pp
.Bl -tag -width XXXX -compact
.Pp
.It Dv gpiodev = gpio.open(path)
Open the gpio device and return an object to access its pins.
.Pp
.It Dv 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
.Em gpiodev:info() .
.Pp
.It Dv gpio.close(gpiodev)
Close the gpio device.
.Pp
.It Dv 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
.Xr gpioctl 8
which also number pins starting at zero.
The following flags are defined:
.Pp
.Bl -tag -width XXXX -compact
.It Dv gpio.PIN_INPUT
Pin is an input.
.Pp
.It Dv gpio.PIN_OUTPUT
Pin is an output.
.Pp
.It Dv gpio.PIN_INOUT
Pin is birectional.
.Pp
.It Dv gpio.PIN_OPENDRAIN
Pin is an open-drain output.
.Pp
.It Dv gpio.PIN_PUSHPULL
Pin is a push-pull output.
.Pp
.It Dv gpio.PIN_TRISTATE
Pin is tri-state (output disabled).
.Pp
.It Dv gpio.PIN_PULLUP
Pin has an internal pull-up enabled.
.Pp
.It Dv gpio.PIN_PULLDOWN
Pin has an internal pull-down enabled.
.Pp
.It Dv gpio.PIN_INVIN
Invert input.
.Pp
.It Dv gpio.PIN_INVOUT
Invert output.
.Pp
.It Dv gpio.PIN_USER
Pin accessible by users.
.Pp
.It Dv gpio.PIN_PULSATE
Pulsate pin at a hardware set frequency.
.Pp
.It Dv gpio.PIN_SET
Pin is set.
.El
.Pp
.It Dv gpio.unset(gpiodev, pin)
Unset gpio pin.
.Pp
.It Dv stat = gpio.read(gpiodev, pin)
Read the current pin state.
.Pp
.It Dv oldstate = gpio.write(gpiodev, pin, state)
Write the pin state returning the old state.
The following states are defined:
.Pp
.Bl -tag -width XXXX -compact
.It Dv gpio.PIN_LOW
Pin is in the low state.
.Pp
.It Dv gpio.PIN_HIGH
Pin is in the high state.
.El
.Pp
.It Dv gpio.toggle(gpiodev, pin)
Toggle pin state.
.Pp
.It Dv gpio.attach(gpiodev, driver, offset, mask [, flags])
Attach a device driver with offset, mask, and optional flags at a pin.
.El
.Sh EXAMPLES
The following example code opens
.Pa /dev/gpio0
and prints all pin values:
.Bd -literal
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
.Ed
.Sh SEE ALSO
.Xr lua 1 ,
.Xr luac 1 ,
.Xr intro 3lua ,
.Xr gpio 4
.Sh HISTORY
A
.Nm
manual appeared in
.Nx 7.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
Lua binding was written by
.An Marc Balmer Aq Mt mbalmer@NetBSD.org .