RuntimeError: Not running on a RPi!

When working with GPIO pins on a Raspberry Pi using Python, you might encounter an error: RuntimeError: Not running on a RPi!. This issue often stems from a lack of proper read-write permissions for accessing the GPIO memory, specifically /dev/gpiomem. Here's a straightforward solution to grant the necessary permissions:

Steps to Grant Access:

1. Change Group Ownership:

• The /dev/gpiomem file needs to have its group ownership changed to your user's group. This can be done using the command:

sudo chown root:$USER /dev/gpiomem

• This command changes the group owner of /dev/gpiomem to your user's primary group.

2. Allow Group Read-Write Access:

• Next, you need to modify the permissions to allow read-write access for the group:

sudo chmod g+rw /dev/gpiomem

• This command changes the group owner of /dev/gpiomem to your user's primary group.

1. Allow Group Read-Write Access:

• Next, you need to modify the permissions to allow read-write access for the group:
• sudo chmod g+rw /dev/gpiomem
• This command grants read-write permissions to the group owner of /dev/gpiomem.

Persistence Issue:

• While the above steps are effective, they might not persist after a reboot, meaning you could face the same error again and have to repeat the process. This lack of persistence can be a hassle for regular Raspberry Pi users.

Seeking a Permanent Solution:

1. Persistent Permission Setting with udev Rule:

• To make the permission change persistent across reboots, a udev rule was created.
• A file named 99-gpiomem.rules was created in /etc/udev/rules.d/ with the following content:

sudo nano /etc/udev/rules.d/99-com.rules

//add this rule in the editor and save and exit
KERNEL=="gpiomem", OWNER="root", GROUP="dialout"

• This rule sets the ownership to root and the group to dialout for the gpiomem device, ensuring the correct permissions are applied at boot.

2. Testing the udev Rule:

• The new udev rule was tested with the following command:

sudo udevadm trigger /dev/gpiomem

3. Adding User to the dialout Group:

• To provide the user with the necessary permissions, the user was added to the dialout group using:

sudo adduser $USER dialout

• Replace $USER with your actual username if necessary.

4. Reboot or Log Out and In:

• A reboot or log out/in is required for these changes to take effect.