u-boot/doc/usage/cmd/gpio.rst
Heinrich Schuchardt 1e120337f9 doc: man-page for gpio command
Provide a man-page for the gpio command.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2022-08-13 11:09:49 +02:00

90 lines
1.7 KiB
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.. SPDX-License-Identifier: GPL-2.0+:
gpio command
============
Synopsis
--------
::
gpio <input|set|clear|toggle> <pin>
gpio read <name> <pin>
gpio status [-a] [<bank>|<pin>]
The gpio command is used to access General Purpose Inputs/Outputs.
gpio input
----------
Switch the GPIO *pin* to input mode.
gpio set
--------
Switch the GPIO *pin* to output mode and set the signal to 1.
gpio clear
----------
Switch the GPIO *pin* to output mode and set the signal to 0.
gpio toggle
-----------
Switch the GPIO *pin* to output mode and reverse the signal state.
gpio read
---------
Read the signal state of the GPIO *pin* and save it in environment variable
*name*.
gpio status
-----------
Display the status of one or multiple GPIOs. By default only claimed GPIOs
are displayed.
-a
Display GPIOs irrespective of being claimed.
bank
Name of a bank of GPIOs to be displayed.
pin
Name of a single GPIO to be displayed or manipulated.
Examples
--------
Switch the status of a GPIO::
=> gpio set a5
gpio: pin a5 (gpio 133) value is 1
=> gpio clear a5
gpio: pin a5 (gpio 133) value is 0
=> gpio toggle a5
gpio: pin a5 (gpio 133) value is 1
=> gpio read myvar a5
gpio: pin a5 (gpio 133) value is 1
=> echo $myvar
1
=> gpio toggle a5
gpio: pin a5 (gpio 133) value is 0
=> gpio read myvar a5
gpio: pin a5 (gpio 133) value is 0
=> echo $myvar
0
Configuration
-------------
The *gpio* command is only available if CONFIG_CMD_GPIO=y.
The *gpio read* command is only available if CONFIG_CMD_GPIO_READ=y.
Return value
------------
If the command succeds the return value $? is set to 0. If an error occurs, the
return value $? is set to 1.