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/clock/toggle/blink ...

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

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

gpio readall

gpio unexportall/exports

gpio export/edge/unexport ...

gpio wfi ...

gpio drive group value

gpio usbp high | low

gpio pwm-bal/pwm-ms

gpio pwmr range

gpio load i2c/spi ...

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 and load the SPI and I2C kernel modules if required. Additionally, it can be used to set the exports in the /sys/class/gpio system directory to allow subsequent programs to use the /sys/class/gpio interface without needing to be run as root.

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. Note: The BCM_GPIO pin numbers are always used with the export and edge commands.

-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 BCM_GPIO pin numbers are always used with the export and edge commands.

-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. See the web page on http://wiringpi.com/the-gpio-utility/

-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.

unexportall
    Un-Export all the GPIO pins in the /sys/class/gpio directory.

exports
    Print a list (if any) of all the exported GPIO pins and their current values.

export
    Export a GPIO pin in the /sys/class/gpio directory. Use like the mode command above however only in, out, high and low are supported at this time. Note that the pin number is the BCM_GPIO number and not the wiringPi number. The high and low commands pre-set the output value at the same time as the export to output mode. Once a GPIO pin has been exported, the gpio program changes the ownership of the /sys/class/gpio/gpioX/value and if present in later kernels, the /sys/class/gpio/gpioX/edge pseudo files to that of the user running the gpio program. This means that you can have a small script of gpio exports to setup the gpio pins as your program requires without the need to run anything as root, or with the sudo command.

edge
    This exports a GPIO pin in the /sys/class/gpio directory, set the direction to input and set the edge interrupt method to none, rising, falling or both. Use like the export command above and note that BCM_GPIO pin number is used not not wiringPi pin numbering. Like the export commands above, ownership is set to that of the calling user, allowing subsequent access from user programs without requiring root/sudo.

unexport
    Un-Export a GPIO pin in the /sys/class/gpio directory.

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.

load i2c [baudrate]
    This loads the i2c or drivers into the kernel and changes the permissions on the associated /dev/ entries so that the current user has access to them. Optionally it will set the I2C baudrate to that supplied in Kb/sec (or as close as the Pi can manage) The default speed is 100Kb/sec. Note: On recent kernels with the device tree enabled you should use the raspi-config program to load/unload the I2C device at boot time.

load spi
    This loads the spi drivers into the kernel and changes the permissions on the associated /dev/ entries so that the current user has access to them. It used to have the ability to change the buffer size from the default of 4096 bytes to an arbitrary value, however for some time the Pi Foundation have compiled the SPI device driver into the kernel and this has fixed the buffer size. The way to change it now is to edit the /boot/cmdline.txt file and add on spdev.bufsiz=8192 to set it to e.g. 8192 bytes then reboot. Note: On recent kernels with the device tree enabled you should use the raspi-config program to load/unload the SPI device at boot time.

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 export 17 out # Set GPIO Pin 17 to output

gpio export 0 in # Set GPIO Pin 0 (SDA0) to input.

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

NOTES
When using the export, edge or unexport commands, the pin numbers are always native BCM_GPIO numbers and never wiringPi pin numbers. 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 home page

    http://wiringpi.com/

AUTHOR
Gordon Henderson

REPORTING BUGS
Please report bugs to <projects@drogon.net>

COPYRIGHT
Copyright (c) 2012-2015 Gordon Henderson 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.