GPIO(1)

NAME
gpio - Command-line access to Raspberry Pi's GPIO

SYNOPSIS
gpio -v

gpio [ -g | -1 ] mode/read/write/aread/awrite/wb/pwm/pwnTone/clock/toggle/blink ...

gpio [ -x extension:params ] mode/read/write/aread/awrite/pwm/toggle/blink ...

gpio [ -p ] read/write/toggle/blink ...

gpio [ -p ] pwnTone pin frequency ...

gpio readall

gpio wfi ...

gpio drive group value

gpio usbp high | low

gpio pwm-bal/pwm-ms

gpio pwmr range

gpio i2cd

gpio gbr channel

gpio gbw channel value

DESCRIPTION
GPIO is a swiss army knife of a command line tool to allow the user easy access to the GPIO pins on the Raspberry Pi and the SPI A/D and D/A converters on the Gertboard. It's designed for simple testing and diagnostic purposes, but can be used in shell scripts for general if somewhat slow control of the GPIO pins. It can also control the IO's on the PiFace IO board.

OPTIONS

-v  Output the current version including the board revision of the Raspberry Pi.

-g  Use the BCM_GPIO pins numbers rather than wiringPi pin numbers.

-1  Use the physical pin numbers rather than wiringPi pin numbers. Note: that this applies to the P1 connector only. It is not possible to use pins on the Revision 2 P5 connector this way, and as with -g the

-x extension
    This causes the named extension to be initialised. Extensions comprise of a name (e.g. mcp23017) followed by a colon, then the pin-base, then more optional parameters depending on the extension type.

-p  Use the PiFace interface board and its corresponding pin numbers. The PiFace will always appear at pin number 200 in the gpio command. You can assign any pin numbers you like in your own programs though.

read <pin>
    Read the digital value of the given pin and print 0 or 1 to represent the respective logic levels.

write <pin> <value>
    Write the given value (0 or 1) to the pin. You need to set the pin to output mode first.

toggle <pin>
    Changes the state of a GPIO pin; 0 to 1, or 1 to 0. Note unlike the blink command, the pin must be in output mode first.

blink <pin>
    Blinks the given pin on/off. Press Control-C to exit. Note: This command explicitly sets the pin to output mode.

aread <pin>
    Read the analog value of the given pin. This needs to be used in conjunction with a -x flag to add in an extension that handles analog inputs. e.g. gpio -x mcp3002:200:0 aread 200 will read the first analog input on an mcp3002 SPI ADC chip.

awrite <pin> <value>
    Write the analog value to the given pin. This needs to be used in conjunction with a -x flag to add in an extension that handles analog inputs. e.g. gpio -x mcp4802:200:0 awrite 200 128 will write the value 128 to the first DAC port on an mcp4802 chip on the Pi's SPI bus 0.

wb <value>
    Write the given byte to the 8 main GPIO pins. You can prefix it with 0x to specify a hexadecimal number. You need to set pins to output mode first.

readall
    Output a table of all GPIO pins values. The values represent the actual values read if the pin is in input mode, or the last value written if the pin is in output mode. The readall command is usable with an extension module (via the -x parameter), but it's unable to determine pin modes or states, so will perform both a digital and analog read on each pin in-turn.

pwm <pin> <value>
    Write a PWM value (0-1023) to the given pin. The pin needs to be put into PWM mode first.

clock <pin> <frequency>
    Set the output frequency on the given pin. The pin needs to be put into clock mode first.

mode <pin> <mode>
    Set a pin into input, output or pwm mode. Can also use the literals up, down or tri to set the internal pull-up, pull-down or tristate (off) controls. The ALT modes can also be set using alt0, alt1, ... alt5.

wfi <pin> <mode>
    This set the given pin to the supplied interrupt mode: rising, falling or both then waits for the interrupt to happen. It's a non-busy wait, so does not consume and CPU while it's waiting.

drive
    group value Change the pad driver value for the given pad group to the supplied drive value. Group is 0, 1 or 2 and value is 0-7. Do not use unless you are absolutely sure you know what you're doing.

usbp
    high | low Change the USB current limiter to high (1.2 amps) or low (the default, 600mA) This is only applicable to the Model B+ and the Model B, v2.

pwm-bal/pwm-ms
    Change the PWM mode to balanced (the default) or mark:space ratio (traditional)

pwmr
    Change the PWM range register. The default is 1024.

i2cd
    Executes i2c-detect for the default I2C port on the P1 connector.

gbr channel This reads the analog to digital converter on the Gertboard on the given channel. The board jumpers need to be in-place to do this operation.

gbw channel value This writes the supplied value to the output channel on the Gertboards SPI digital to analogue converter. The board jumpers need to be in-place to do this operation.

WiringPi vs. BCM_GPIO Pin numbering vs. Physical pin numbering

The quickest way to get a list of the pin differences is to run the command

gpio readall

FILES

gpio
    executable

EXAMPLES

gpio mode 4 output # Set pin 4 to output

gpio -g mode 23 output # Set GPIO pin 23 to output (same as WiringPi pin 4)

gpio mode 1 pwm # Set pin 1 to PWM mode

gpio pwm 1 512 # Set pin 1 to PWM value 512 - half brightness

gpio -g read 0 # Read GPIO Pin 0 (SDA0)

NOTES
As of kernels 4.1.7, a user-level GPIO access mechanism is available, however wiringPi will not use this by default - because at this time there appears to be issues when trying to program the PWM or clock output hardware. If you can live without PWM or GPIO clocks and you want to use the GPIO from a non-root program, then you need to make sure that the module bcm2835_gpiomem is loaded at boot time. This should happen automatically when you enable the device tree in raspi-config. You may also need some additional information in /etc/udev/rules.d/ to change the mode and ownership of the /dev/gpiomem file. Finally, you need to set the environment variable WIRINGPI_GPIOMEM. This will go-away in future releases once the /dev/gpiomem interface is fully operational.

SEE ALSO

WiringPi's development

    https://github.com/WiringPi/WiringPi/

AUTHOR
Gordon Henderson and contributors

REPORTING BUGS
Please report bugs to https://github.com/WiringPi/WiringPi/issues

COPYRIGHT
Copyright (c) 2012-2025 Gordon Henderson and contributors
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

TRADEMARKS AND ACKNOWLEDGEMENTS
Raspberry Pi is a trademark of the Raspberry Pi Foundation. See http://raspberrypi.org/ for full details.