gpioctl(8) - NetBSD Manual Pages

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


NAME

     gpioctl -- control GPIO devices


SYNOPSIS

     gpioctl [-hq] [-d device] [pin] [0 | 1 | 2]
     gpioctl [-hq] [-d device] -c pin [flags]


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, 1-wire thermal sensors,
     etc., to its pins.

     Each GPIO device has an associated device file in the /dev directory.  By
     default gpioctl uses /dev/gpio0, which corresponds to the first found
     GPIO device in the system.  If more than one GPIO device is present, an
     alternative device file can be specified with the -d option in order to
     access a particular GPIO device.

     When executed without any arguments, gpioctl reads information about the
     GPIO device and displays it.

     GPIO pins can be either ``read'' or ``written'' with the values of logi-
     cal 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 has a special meaning: it ``toggles'' the
     pin, i.e. changes its state to the opposite.

     Each pin can be configured with different flags with the -c option.  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

     Note that not all the flags can be supported by the particular GPIO con-
     troller.  The list of supported flags is always displayed when executing
     gpioctl with the -c option.  If only a pin number is specified on the
     command line, the current pin flags will be displayed.  To change pin
     flags, a new flags set separated by spaces must be specified after the
     pin number.

     The -q option causes gpioctl to operate quietly i.e. nothing is printed
     to stdout.  The -h option displays a usage summary.


FILES

     /dev/gpiou  GPIO device unit u file.


EXAMPLES

     Configure pin 20 to have push-pull output:

           # gpioctl -c 20 out pp

     Write logical 1 to pin 20:

           # gpioctl 20 1


SEE ALSO

     elansc(4), gcscpcib(4), gpio(4), gscpcib(4), nsclpcsio(4)


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>.

NetBSD 5.0                      January 9, 2008                     NetBSD 5.0