The gpio-control interface

The gpio-control interface provides privileged access to all aspects of GPIO pins. For accessing specific GPIO pins with limited scope, see The gpio interface instead.

Due to its wide-ranging access, it is a super-privileged interface, and as such, is restricted by default. This interface requires modification of its snap declaration for distribution via the Snap Store.

This interface is used for:

  • Fine-grained control of GPIO pins (input and output).

  • Building custom hardware interfaces, such as LEDs, relays, or sensors.

  • Low-level interaction with GPIO hardware using character devices or sysfs.

Developer Details

Auto-connect: no
Super-privileged: yes

Path Access

The gpio-control interface grants read-write access to the following paths:

  1. Sysfs Interface:

  • /sys/class/gpio/ paths for exporting, setting direction, toggling values, and more:

    • /sys/class/gpio/{,un}export

    • /sys/class/gpio/gpio\[0-9\]\*/{active\_low,direction,value,edge}

  • Additional symlink paths (platform-specific):

    • /sys/devices/platform/\*\*/gpio/gpio\[0-9\]\*/{active\_low,direction,value,edge}

  1. Gpiochip Interface:

  • /dev/gpiochip\[0-9\]\ paths for direct hardware interaction through the gpiod API.

The following UDev rules are applied to enable device access:

  • SUBSYSTEM=="gpio", KERNEL=="gpiochip[0-9]*"

Requires snapd version 2.41+. gpoichip\* access requires snapd version 2.65+.

The following is an example of a snapcraft.yaml configuration for the GPIO control interface, following the descriptive interface reference practice for clarity:

name: gpio-control-app
version: '1.0'
summary: An example snap for controlling GPIO pins
description: |
  This snap demonstrates how to use the GPIO Control interface to manage GPIO hardware for custom applications.

grade: stable
confinement: strict

plugs:
  gpio-pins-control:
    interface: gpio-control

apps:
  gpio-app:
    command: bin/gpio-app
    plugs:
      - gpio-pins-control

After building and installing the snap, use the following command to connect the interface manually:

sudo snap connect gpio-control-app:gpio-pins-control

This ensures clarity and aligns with the best practices for naming interface references when using snap connections, snap interfaces, snap connect, or snap disconnect.