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Embassy

Embassy is the next-generation framework for embedded applications. Write safe, correct and energy-efficient embedded code faster, using the Rust programming language, its async facilities, and the Embassy libraries.

<a href="https://embassy.dev/dev/index.html">Documentation</a> - <a href="https://docs.embassy.dev/">API reference</a> - <a href="https://embassy.dev/">Website</a> - <a href="https://matrix.to/#/#embassy-rs:matrix.org">Chat</a>

Rust + async ❤️ embedded

The Rust programming language is blazingly fast and memory-efficient, with no runtime, garbage collector or OS. It catches a wide variety of bugs at compile time, thanks to its full memory- and thread-safety, and expressive type system.

Rust's <a href="https://rust-lang.github.io/async-book/">async/await</a> allows for unprecedently easy and efficient multitasking in embedded systems. Tasks get transformed at compile time into state machines that get run cooperatively. It requires no dynamic memory allocation, and runs on a single stack, so no per-task stack size tuning is required. It obsoletes the need for a traditional RTOS with kernel context switching, and is <a href="https://tweedegolf.nl/en/blog/65/async-rust-vs-rtos-showdown">faster and smaller than one!</a>

Batteries included

Sneak peek

use defmt::info;
use embassy_executor::Spawner;
use embassy_time::{Duration, Timer};
use embassy_nrf::gpio::{AnyPin, Input, Level, Output, OutputDrive, Pin, Pull};
use embassy_nrf::Peripherals;

// Declare async tasks
#[embassy_executor::task]
async fn blink(pin: AnyPin) {
    let mut led = Output::new(pin, Level::Low, OutputDrive::Standard);

    loop {
        // Timekeeping is globally available, no need to mess with hardware timers.
        led.set_high();
        Timer::after_millis(150).await;
        led.set_low();
        Timer::after_millis(150).await;
    }
}

// Main is itself an async task as well.
#[embassy_executor::main]
async fn main(spawner: Spawner) {
    let p = embassy_nrf::init(Default::default());

    // Spawned tasks run in the background, concurrently.
    spawner.spawn(blink(p.P0_13.degrade())).unwrap();

    let mut button = Input::new(p.P0_11, Pull::Up);
    loop {
        // Asynchronously wait for GPIO events, allowing other tasks
        // to run, or the core to sleep.
        button.wait_for_low().await;
        info!("Button pressed!");
        button.wait_for_high().await;
        info!("Button released!");
    }
}

Examples

Examples are found in the examples/ folder seperated by the chip manufacturer they are designed to run on. For example:

Running examples

cargo install probe-rs --features cli

cd examples/nrf52840

For example:

cargo run --release --bin blinky

For more help getting started, see Getting Started and Running the Examples.

Developing Embassy with Rust Analyzer based editors

The Rust Analyzer is used by Visual Studio Code and others. Given the multiple targets that Embassy serves, there is no Cargo workspace file. Instead, the Rust Analyzer must be told of the target project to work with. In the case of Visual Studio Code, please refer to the .vscode/settings.json file's rust-analyzer.linkedProjectssetting.

Minimum supported Rust version (MSRV)

Embassy is guaranteed to compile on the latest stable Rust version at the time of release. It might compile with older versions but that may change in any new patch release.

Several features require nightly:

These are enabled by activating the nightly Cargo feature. If you do so, Embassy is guaranteed to compile on the exact nightly version specified in rust-toolchain.toml. It might compile with older or newer nightly versions, but that may change in any new patch release.

Why the name?

EMBedded ASYnc! :)

License

This work is licensed under either of

at your option.