https://github.com/sunfishcode/hello-embedded

Hello Embedded!
https://github.com/sunfishcode/hello-embedded

Last synced: 5 days ago
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Hello Embedded!

• Host: GitHub
• URL: https://github.com/sunfishcode/hello-embedded
• Owner: sunfishcode
• Created: 2024-02-17T00:40:05.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2024-02-29T21:50:50.000Z (9 months ago)
• Last Synced: 2024-11-01T12:52:20.439Z (12 days ago)
• Language: Rust
• Size: 77.1 KB
• Stars: 21
• Watchers: 4
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

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README

        
# Hello Embedded! 👋

This repository contains a sketch of an embedded API described in [Wit],

and a simple example Wasm application that builds with it that blinks

an LED, and a Wasmtime-based simulator that can run it. This is a super

early demo, and hasn't been optimized at all for code size yet. Its

purpose right now is to start some discussions.

[Wit]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md

## The Wits

The API is described in Wit interfaces in the wit directory, and is based off

of the [embedded-hal] API.

## The guest

The example application is in the guest directory. Building it currently

requires [cargo component 0.8]. Build with `cargo component build`.

[cargo component 0.8]: https://github.com/bytecodealliance/cargo-component/releases/tag/v0.8.0

```sh

$ cd guest

$ cargo component build --release

[...]

$ cd ..

```

That produces a component in `guest/target/wasm32-wasi/release/hello_embedded.wasm`.

We can examine it with `wasm-tools`:

```sh

$ wasm-tools component wit guest/target/wasm32-wasi/release/hello_embedded.wasm

package root:component;

world root {

  import sketch:embedded/[email protected];

  import sketch:embedded/[email protected];

  export sketch:embedded/[email protected];

}

```

Here we can see it's exporting the `run` interface, which has the `run`

entrypoint function, and importing the `digital` and `delay` and interfaces,

which it uses to set the led and control its speed, respectively.

## The host simulator

Once the guest is built, it can be run in the host simulator:

```sh

$ cd host

$ cargo run

[...]

```

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## The Linux host

⚠ The following is *entirely untested* at this time!!! ⚠

If you can run this on a Linux board with a GPIO pin 0 wired up to

an LED, and if luck smiles on us, this should run the guest which

should make that LED blink:

```sh

$ cd linux-host

$ cargo run

[...]

```

## Bonus points

This example also demonstrates [Typed Main]. The `run` function takes

two handle arguments, providing the component with exactly what it

needs.

[Typed Main]: https://sunfishcode.github.io/typed-main-wasi-presentation/chapter_1.html

[embedded-hal]: https://docs.rs/embedded-hal/latest/embedded_hal/