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. gpio status command output fields are:

<name>: <function>: <value> [x] <label>

function can take the following values:

output: pin configured in gpio output, value indicates the pin’s level
input: pin configured in gpio input, value indicates the pin’s level
func: pin configured in alternate function, followed by label which shows pinmuxing label.
unused: pin not configured

[x] or [ ] indicate respectively if the gpio is used or not.

label shows the gpio label.

Parameters

-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

Show the GPIO status:

=> gpio status
Bank GPIOA:
GPIOA1: func rgmii-0
GPIOA2: func rgmii-0
GPIOA7: func rgmii-0
GPIOA10: output: 0 [x] hdmi-transmitter@39.reset-gpios
GPIOA13: output: 1 [x] red.gpios

Bank GPIOB:
GPIOB0: func rgmii-0
GPIOB1: func rgmii-0
GPIOB2: func uart4-0
GPIOB7: input: 0 [x] mmc@58005000.cd-gpios
GPIOB11: func rgmii-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.