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GPIOCTL(8) System Manager's Manual GPIOCTL(8)

gpioctl — control GPIO devices

gpioctl [-qs] device

gpioctl [-q] device attach device offset mask [flag]

gpioctl [-qs] device pin [0 | 1 | 2]

gpioctl [-qs] device pin [on | off | toggle]

gpioctl [-q] device pin set [flags] [name]

gpioctl [-q] device pin unset

The gpioctl program allows manipulation of GPIO (General Purpose Input/Output) device pins. Such devices can be either part of the chipset or embedded CPU, or a separate chip. The usual way of using GPIO is to connect some simple devices such as LEDs and 1-wire thermal sensors to its pins.

Each GPIO device has an associated device file in the /dev directory. device can be specified with or without the /dev prefix. For example, /dev/gpio0 or gpio0.

GPIO pins can be either “read” or “written” with the values of logical 0 or 1. If only a pin number is specified on the command line, the pin state will be read from the GPIO controller and displayed. To write to a pin, a value must be specified after the pin number. Values can be either 0 or 1. A value of 2 “toggles” the pin, i.e. changes its state to the opposite. Instead of the numerical values, the word on, off, or toggle can be used.

Only pins that have been configured at securelevel 0, typically during system startup, are accessible once the securelevel has been raised. Pins can be given symbolic names for easier use. Besides using individual pins, device drivers that use GPIO pins can be attached to a gpio(4) device using the gpioctl command. Such drivers can be detached at runtime using the drvctl(8) command.

The following configuration flags are supported by the GPIO framework:

in
input direction
out
output direction
inout
bi-directional
od
open-drain output
pp
push-pull output
tri
tri-state (output disabled)
pu
internal pull-up enabled
pd
internal pull-down enabled
iin
invert input
iout
invert output
pulsate
pulsate output at a hardware-defined frequency and duty cycle
alt0 - alt7
select alternate pin function 0 to 7

Note that not all the flags may be supported by the particular GPIO controller.

When executed with only the gpio(4) device name as argument, gpioctl reads information about the GPIO device and displays it. At securelevel 0 the number of physically available pins is displayed, at higher securelevels the number of configured (set) pins is displayed.

The options are as follows:

Operate quietly i.e. nothing is printed to stdout.
Only output a single number on stdout, representing either the state of the pin or the number of available pins if no pin number was passed as argument. This option is useful e.g. when gpioctl is used in shell scripts to query the state of a pin.

/dev/gpiou
GPIO device unit u file.

Configure pin 20 to have push-pull output:

# gpioctl gpio0 20 set out pp

Write logical 1 to pin 20:

# gpioctl gpio0 20 1

Attach a onewire(4) bus on a gpioow(4) device on pin 4:

# gpioctl gpio0 attach gpioow 4 0x01

Detach the gpioow0 device:

# drvctl -d gpioow0

Configure pin 5 as output and name it error_led:

# gpioctl gpio0 5 set out error_led

Toggle the error_led:

# gpioctl gpio0 error_led 2

gpio(4), drvctl(8)

The gpioctl command first appeared in OpenBSD 3.6 and NetBSD 4.0.

The gpioctl program was written by Alexander Yurchenko <grange@openbsd.org>. Device attachment was added by Marc Balmer <marc@msys.ch>.

February 12, 2019 NetBSD-9.2