GPIO usage This guide covers the Linux interface for GPIO operations using bash
Available GPIO's
The following output provides a list of all GPIO's that are available to the Jetson. This includes Tegra GPIO's as well as external driven GPIO extender.
If you want to do this Linux interface on a external connected GPIO extender, requires changes to the DeviceTree. A more detailed Instruction on how to implement such a device can be found in the Linux kernel Documentation .
Syntax: sudo cat /sys/kernel/debug/gpio
Copy test@test-desktop:~$ sudo cat /sys/kernel/debug/gpio
[sudo] password for test:
gpiochip1: GPIOs 316-347, parent: platform/c2f0000.gpio, tegra234-gpio-aon:
gpio-316 (PAA.00 )
gpio-317 (PAA.01 )
gpio-318 (PAA.02 )
gpio-319 (PAA.03 )
gpio-320 (PAA.04 )
gpio-321 (PAA.05 |fixed-regulators:reg) out hi
gpio-322 (PAA.06 )
gpio-323 (PAA.07 )
gpio-324 (PBB.00 )
gpio-325 (PBB.01 )
gpio-326 (PBB.02 )
gpio-327 (PBB.03 )
gpio-328 (PCC.00 )
gpio-329 (PCC.01 )
gpio-330 (PCC.02 )
gpio-331 (PCC.03 |mux ) out hi
gpio-332 (PCC.04 )
gpio-333 (PCC.05 )
gpio-334 (PCC.06 )
gpio-335 (PCC.07 )
gpio-336 (PDD.00 )
gpio-337 (PDD.01 )
gpio-338 (PDD.02 )
gpio-339 (PEE.00 )
gpio-340 (PEE.01 )
gpio-341 (PEE.02 )
gpio-342 (PEE.03 )
gpio-343 (PEE.04 |power-key ) in hi IRQ ACTIVE LOW
gpio-344 (PEE.05 )
gpio-345 (PEE.06 )
gpio-346 (PEE.07 )
gpio-347 (PGG.00 )
gpiochip0: GPIOs 348-511, parent: platform/2200000.gpio, tegra234-gpio:
gpio-348 (PA.00 |fixed-regulators:reg) out lo
gpio-349 (PA.01 )
gpio-350 (PA.02 )
gpio-351 (PA.03 )
# And so on... The GPIO numbers listed in the Linux operating system do not match with the numbers of the Jetson socket pins.
Export GPIO
At first, you have to export the GPIO that you want to use in the Linux file system in order to configure and read or write data from it.
Syntax: echo <GPIO_NR> > /sys/class/gpio/export
Copy nvidia@nvidia-desktop:~$ echo 414 > /sys/class/gpio/export
nvidia@nvidia-desktop:~$ Change GPIO direction
The GPIO direction decides if the GPIO should be used as Input or Output
Keep in mind that some Carrierboards are using unidirectional level shifters -> In this case only one direction will work properly.
More Information about such implementations are documented in the corresponding manual of your Carrierboard.
Syntax
jetpack 4.6 <= Jetpack 5.0 >= External driven extender
Copy echo <in|out> > /sys/class/gpio/gpio<GPIO_NR>/direction Copy echo <in|out> > /sys/class/gpio/gpio<GPIO_NAME>/direction Copy echo <in|out> > /sys/class/gpio/gpio<GPIO_NR>/direction Configure as Input
set GPIO direction as input
Copy nvidia@nvidia-desktop:~$ echo in > /sys/class/gpio/gpio414/direction
nvidia@nvidia-desktop:~$ Configure as Output
set GPIO direction as output
Copy nvidia@nvidia-desktop:~$ echo out > /sys/class/gpio/gpio414/direction
nvidia@nvidia-desktop:~$ Set GPIO Value
The logical GPIO level can be configure in the following ways. Keep in mind that its required to configure the GPIO as output before changing its output value.
Syntax
jetpack 4.6 <= Jetpack 5.0 >= External driven extender
Copy echo <0|1> > /sys/class/gpio/gpio<GPIO_NR>/value Copy echo <0|1> > /sys/class/gpio/gpio<GPIO_NAME>/value Copy echo <0|1> > /sys/class/gpio/gpio<GPIO_NR>/value Set low
Set output as logical low
Copy nvidia@nvidia-desktop:~$ echo 0 > /sys/class/gpio/gpio414/value
nvidia@nvidia-desktop:~$ Set high
Set output as logical high
Copy nvidia@nvidia-desktop:~$ echo 1 > /sys/class/gpio/gpio414/value
nvidia@nvidia-desktop:~$ Read GPIO state
Syntax
jetpack 4.6 <= Jetpack 5.0 >= External driven extender
Copy cat /sys/class/gpio/gpio<GPIO_NR>/value Copy cat /sys/class/gpio/gpio<GPIO_NAME>/value Copy cat /sys/class/gpio/gpio<GPIO_NR>/value The following example reads the current state of the GPIO. This operation works in output as well as in input mode.
Copy nvidia@nvidia-desktop:~$ cat /sys/class/gpio/gpio414/value
0
nvidia@nvidia-desktop:~$ cat /sys/class/gpio/gpio414/value
1
