posborne / rust-sysfs-gpio

A Rust Interface to the Linux sysfs GPIO interface (https://www.kernel.org/doc/Documentation/gpio/sysfs.txt)

sysfs_gpio

• API Documentation

The sysfs_gpio crate provides access to the Linux sysfs GPIO interface (https://www.kernel.org/doc/Documentation/gpio/sysfs.txt). It seeks to provide an API that is safe, convenient, and efficient and supports exporting, unexporting, reading, writing and waiting for interrupts on pins.

Many devices such as the Raspberry Pi or Beaglebone Black provide userspace access to a number of GPIO peripherals. The standard kernel API for providing access to these GPIOs is via sysfs.

You might want to also check out the gpio-utils Project for a convenient way to associate names with pins and export them as part of system boot. That project uses this library.

Install/Use

To use sysfs_gpio, first add this to your Cargo.toml:

[dependencies]
sysfs_gpio = "0.5"

Then, add this to your crate root:

extern crate sysfs_gpio;

Example/API

Blinking an LED:

extern crate sysfs_gpio;

use sysfs_gpio::{Direction, Pin};
use std::thread::sleep;
use std::time::Duration;

fn main() {
    let my_led = Pin::new(127); // number depends on chip, etc.
    my_led.with_exported(|| {
        loop {
            my_led.set_value(0).unwrap();
            sleep(Duration::from_millis(200));
            my_led.set_value(1).unwrap();
            sleep(Duration::from_millis(200));
        }
    }).unwrap();
}

More Examples:

• Blink an LED
• Poll a GPIO Input
• Receive interrupt on GPIO Change
• Poll several pins asynchronously with Tokio
• gpio-utils Project (uses most features)

Features

The following features are planned for the library:

• Support for exporting a GPIO
• Support for unexporting a GPIO
• Support for setting the direction of a GPIO (in/out)
• Support for reading the value of a GPIO input
• Support for writing the value of a GPIO output
• Support for configuring whether a pin is active low/high
• Support for configuring interrupts on GPIO
• Support for polling on GPIO with configured interrupt
• Support for asynchronous polling using mio or tokio-core (requires enabling the mio-evented or tokio crate features, respectively)

Cross Compiling

Most likely, the machine you are running on is not your development machine (although it could be). In those cases, you will need to cross-compile. The rust-cross guide provides excellent, detailed instructions for cross-compiling.

Running the Example

Cross-compiling can be done by specifying an appropriate target. You can then move that to your device by whatever means and run it.

$ cargo build --target=arm-unknown-linux-gnueabihf --example blinky
$ scp target/arm-unknown-linux-gnueabihf/debug/examples/blinky ...

License

Copyright (c) 2015, Paul Osborne <[e-mail]>

Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
http://www.apache.org/license/LICENSE-2.0> or the MIT license
<LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
option.  This file may not be copied, modified, or distributed
except according to those terms.