NixOS on ARM/Raspberry Pi 4: Difference between revisions

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@@ Line 180: / Line 180: @@
 </nowiki>}}
-=== Gpio ===
+=== Using GPIO pins as non root ===
-Add gpio group and change permission for all users in new gpio group.
-Now all users in gpio group have access to /dev/gpiomem and to gpio pins via sysfs.
+By default, the GPIO pins are enable, but can only be accessed by the root user.
+This can be address by adding a [https://wiki.archlinux.org/title/Udev udev] rule to your configuration that changes the owner ship of <code>/dev/gpiomem</code> and the other required devices.
-{{file|/etc/nixos/configuration.nix|nix|<nowiki>
+The following code adds a group <code>gpio</code> and adds the user <code>mygpiouser</code> to that group.
-   # add gpio group
+You probably want to put your own user name here.
+The <code>extraRules</code> change the owner of <code>gpiomem</code> and all other files needed for GPIO to work to <code>root:gpio</code> and changes the permissions to <code>0660</code>.
+Therefore, the root user and anyone in the gpio group can now access the GPIO pins.
+<syntaxHighlight lang="nix">
+   # Create gpio group
    users.groups.gpio = {};
-   # udev rule for gpio
+   # Change permissions gpio devices
    services.udev.extraRules = ''
      SUBSYSTEM=="bcm2835-gpiomem", KERNEL=="gpiomem", GROUP="gpio",MODE="0660"
@@ Line 196: / Line 202: @@
    '';
-   # add user with gpio group
+   # Add user to group
    users = {
-    mutableUsers = false;
      users.mygpiouser = {
-      isNormalUser = true;
+       extraGroups = [ "gpio" ... ];
-      password = "mygpiouserpasswd";
+      ....
-       extraGroups = [ "wheel" "gpio" ];
      };
    };
+</syntaxHighlight>
-</nowiki>}}
 === HDMI-CEC ===