GPIOOW(4) BSD Kernel Interfaces Manual GPIOOW(4)NAME
gpioow -- 1-Wire bus bit-banging through GPIO pin
SYNOPSIS
gpioow* at gpio? offset 0 mask 0x1
gpioow* at gpio?
onewire* at gpioow?
DESCRIPTION
The gpioow driver allows bit-banging a 1-Wire bus as a master using one GPIO pin. The pin is used as a data signal. The GPIO pin must be
able to drive an output and read an input.
The pin number is specified in the kernel configuration with the offset locator. The mask locator should always be 0x1. The offset and mask
can also be specified when gpioow is attached at runtime using the GPIOATTACH ioctl(2) on the gpio(4) device.
SEE ALSO gpio(4), intro(4), onewire(4)HISTORY
The gpioow driver first appeared in OpenBSD 4.0 and NetBSD 4.0.
AUTHORS
The gpioow driver was written by Alexander Yurchenko <grange@openbsd.org> and was ported to NetBSD by Jeff Rizzo <riz@NetBSD.org>.
BSD July 19, 2009 BSD
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GPIOCTL(8) BSD System Manager's Manual GPIOCTL(8)NAME
gpioctl -- control GPIO devices
SYNOPSIS
gpioctl [-q] device attach device offset mask [flag]
gpioctl [-q] device pin [0 | 1 | 2]
gpioctl [-q] device pin [on | off | toggle]
gpioctl [-q] device pin set [flags] [name]
gpioctl [-q] device pin unset
DESCRIPTION
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. Val-
ues 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.
To
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
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:
-q Operate quietly i.e. nothing is printed to stdout.
FILES
/dev/gpiou GPIO device unit u file.
EXAMPLES
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
SEE ALSO gpio(4), drvctl(8)HISTORY
The gpioctl command first appeared in OpenBSD 3.6 and NetBSD 4.0.
AUTHORS
The gpioctl program was written by Alexander Yurchenko <grange@openbsd.org>. Device attachment was added by Marc Balmer <marc@msys.ch>.
BSD November 13, 2011 BSD