Rust on Embedded Devices

Rust on Embedded Devices

Rust, a programming language known for its safe handling of concurrency and memory, has gained a lot of traction in the embedded development space. This page aims to explore the concept, benefits, and processes involved in using Rust on embedded devices.

Table of Contents

Why Rust for Embedded Devices?

The Rust programming language has several features that make it attractive for embedded systems development:

  1. Memory Safety: Rust provides strong guarantees that it will not encounter null pointers, double free, buffer overflow errors and other common unsafe memory handling mistakes. It accomplishes this without garbage collection, which makes Rust suitable for memory-constrained scenarios such as embedded systems.

  2. Concurrent Programming: Rust has first-class support for concurrent programming, alleviating many of the pitfalls that make multi-threaded programming difficult and error-prone.

  3. Low Overhead: Rust has minimal runtime, which is advantageous for embedded systems where resources are at a premium.

  4. Strong Type System: Rust's type system helps prevent several common programming mistakes at compile-time.

  5. Interoperability: Rust can interoperate with C code, making it easier to incrementally rewrite old C codebases.

Challenges of Rust for Embedded Development

Despite its promising features, there are challenges to using Rust for embedded systems development:

  1. Learning Curve: Rust's syntax and concepts are significantly different from traditional languages like C and C++. This can be a steep learning curve for developers new to Rust.

  2. Tooling: While the tooling ecosystem is improving, it's not as mature or wide-spread as for C and C++.

  3. Library Support: There is still a lack of comprehensive library support specifically tailored to embedded systems.

Getting Started with Rust on Embedded Devices

Before we start developing with Rust on embedded devices, there are a few steps to setup:

  1. Rust Installation: You can install Rust by running the following curl command:

    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
    
  2. Toolchain Installation: To cross-compile for your embedded device, you need a suitable Rust toolchain. You can often use the rustup command to download and install it:

    rustup target add thumbv7m-none-eabi
    

Common Rust Tools for Embedded Development

There are several tools available for Rust-based embedded development:

  • cargo: Rust's package manager, build system and task runner. It's used to manage Rust projects.
  • cargo-binutils: A collection of cargo subcommands that delegate to the corresponding GNU Binutils.
  • cargo-embed: Cargo subcommand for managing and interacting with devices.

Writing Your First Rust Program for an Embedded Device

Now that we have setup our tools, let's write our first Rust program for an embedded device. We will blink an LED.

Our main.rs file looks like this:

#![no_std]
#![no_main]

use cortex_m_rt::entry;
use embedded_hal::digital::v2::OutputPin;
use stm32f4xx_hal::{delay::Delay, prelude::*, stm32};

#[entry]
fn main() -> ! {
    let dp = stm32::Peripherals::take().unwrap();
    let cp = cortex_m::Peripherals::take().unwrap();

    let gpioa = dp.GPIOA.split();
    let mut led = gpioa.pa5.into_push_pull_output();
    let mut delay = Delay::new(cp.SYST);

    loop {
        led.set_high().ok();
        delay.delay_ms(1000u32);
        led.set_low().ok();
        delay.delay_ms(1000u32);
    }
}

This program uses the STM32F4xx microcontroller board's HAL (Hardware Abstraction Library) to blink an LED located on pin PA5.

Deploying the Rust Code to an Embedded Device

After writing your code, to deploy it, follow these steps:

  1. Compile the Program: Use the cargo tool to compile the program:

    cargo build --target thumbv7m-none-eabi
    
  2. Deploy the Program: The deployment method will depend on your specific hardware. You'll often use tools like OpenOCD or cargo-embed to flash the program onto the device.

Important Libraries and Crates

There are several libraries and crates that can be useful when developing Rust for embedded systems:

  • cortex-m: Low-level access to Cortex-M processors.
  • cortex-m-rt: Startup and runtime features for Cortex-M processors.
  • embedded-hal: Hardware abstraction layer for embedded systems.
  • stm32f4xx-hal: Hardware abstraction layer for the STM32F4xx family of microcontrollers.

Conclusion

In conclusion, while Rust brings many promising features to the table for embedded development, it also presents challenges that developers must be ready to face. Nevertheless, the robust safety, performance, and concurrency features of Rust make it a tempting option for embedded development. As the ecosystem around Rust for embedded systems continues to grow, we expect these challenges will be countered with comprehensive tools and libraries.