rust-sysfs-gpio

rust-sysfs-gpio is a rust library/crate providing access to the Linux sysfs GPIO interface (https://www.kernel.org/doc/Documentation). It seeks to provide an API that is safe, convenient, and efficient.

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.

Example/API

The follow example shows the low-level API. This API maps directly to the functionality provided by the sysfs GPIO interface.

```rust

![feature(old_io)]

![feature(io)]

![feature(std_misc)]

![allow(deprecated)] // old_io Timer replacement not stable

extern crate sysfs_gpio;

use sysfsgpio::core::{Direction, Pin}; use std::time::Duration; use std::oldio::Timer; use std::io;

// export a GPIO for use. This will not fail // if already exported fn blinkmyled(led : u64, durationms : i64, periodms : i64) -> io::Result<()> { let myled = Pin::new(led); try!(myled.export()); try!(myled.setdirection(Direction::Low)); let mut tmr = match Timer::new() { Ok(tmr) => tmr, Err() => panic!("Could not create timer!"), }; let iterations = durationms / periodms / 2; for _ in 0..iterations { try!(myled.setvalue(0)); tmr.sleep(Duration::milliseconds(periodms)); // ms try!(myled.setvalue(1)); tmr.sleep(Duration::milliseconds(periodms)); // ms } try!(myled.setvalue(0)); // end with led off try!(myled.unexport()); return Ok(()); }

fn main() { match blinkmyled(66, 5000, 200) { Ok(()) => println!("Blinking Complete!"), Err(err) => println!("I have a blinking problem! {:?}", err), } }

```

Features

The following features are planned for the library:

[x] Support for exporting a GPIO
[x] Support for unexporting a GPIO
[x] Support for setting the direction of a GPIO (in/out)
[x] Support for reading the value of a GPIO input
[x] 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

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 following basic instructions should work for the raspberry pi or beaglebone black:

Install rust and cargo
Install an appropriate cross compiler. On an Ubuntu system, this can be done by doing sudo apt-get install g++-arm-linux-gnueabihf.
Build or install rust for your target. This is necessary in order to have libstd available for your target. For arm-linux-gnueabihf, you can find binaries at https://github.com/japaric/ruststrap. With this approach or building it yourself, you will need to copy the ${rust}/lib/rustlib/arm-unknown-linux-gnueabihf to your system rust library folder (it is namespaced by triple, so it shouldn't break anything).
Tell cargo how to link by adding the lines below to your ~/.cargo/config file.
Run your build cargo build --target=arm-unknown-linux-gnueabi.

The following snippet added to my ~/.cargo/config worked for me:

[target.arm-unknown-linux-gnueabihf] linker = "arm-linux-gnueabihf-gcc"

License

Licensed under the Apache License, Version 2.0 or the MIT license , at your option. This file may not be copied, modified, or distributed except according to those terms.