Jetson.GPIO permissions with Yocto build

Autonomous Machines Jetson & Embedded Systems Jetson Nano
1

Hello,

I’m working on creating an image for the Nano using the Yocto Project and Bitbake. As part of that, I’m trying to include Jetson.GPIO in the image at builtime.

I have the following recipe for the package

SUMMARY = "Recipie to embedded the Python PiP Package Jetson.GPIO"
HOMEPAGE ="https://pypi.org/project/Jetson.GPIO"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://PKG-INFO;md5=a8fc9772bcd540559bdffee9f34755e7"

inherit pypi setuptools3
PYPI_PACKAGE = "Jetson.GPIO"
SRC_URI[md5sum] = "a2ade30de4627f724f98843eca0e222d"
SRC_URI[sha256sum] = "f5d1103bbc2701c0b1603d31ea9043ca9ab670d6204846aa2ff25c2302c91fdc"

This installs the package correctly, but user permissions are still a bit weird. I can confirm that I’ve created a group called “gpio” and that the user is a member using the groups command.

Running the following shows permissions on export/unexport

--w-------    1 root     root          4096 Feb  7 15:50 /sys/class/gpio/export

If I try importing the package in python, I receive a permissions issue saying the user does not have permissions. However it works if I run python with sudo.

I’ve attempted copying 99-gpio.rules into /etc/udev/rules.d and have run the command to reload and trigger the rule change. Still doesn’t work though.

The only success I’ve had is if I attempt to run the bash commands listed inside the 99-gpio.rules file manually. After this, the user has gpio function without sudo

I can always switch it to a more manual install and installing from source, but just felt the pypi method would be easier. Any thoughts?

Note: image is based on core-image-minimal and uses meta-tegra for the hardware bsp.

Can provide any other information on the build as needed! Thanks guys.

Edit I went ahead and tried installing using sudo python3 setup.py install and copying over the rules before running the udevadm commands. Still not working

Edit 2 So I realized that meta-tegra doesn’t expose the spidev device and there was a line in 99-gpio.rules that affects this device. By commenting out the line, copying it over into rules.d and running reload/trigger + a restart it’s working properly. Still a bit weird

3

hello bsmerbeck,

besides working with Jetson-GPIO, could you please enable GPIOs manually.
please refer to below as examples,

* Location of the GPIOs
$ cd /sys/class/gpio

* Generate gpio220 name
$ echo 220 > export

* Enable GPIOs
$ echo out > direction 
$ echo 1 > value

you may also refer to GPIO Changes session to translate from SOM-connector pins to actual GPIO numbers.
thanks