wg VS embassy

Inspired by James Munns's call, and as 2023 is coming to an end, I figure it's a good opportunity to reflect and look forward to 2024. It's been a bit over 1.5 years since I embarked on my embedded Rust journey and it's been nothing less than exciting since. So here it goes.

Because you are an embedded guy. There is the https://github.com/rust-embedded/wg working-group. Rust on embedded is really on a got track forward. There are many chips/vendors that are supported both in no std / std rust world, but still there is a lot of niche things where you can actively help to be the first to get it run in Rust.

To specifically answer your question, here:

* <http://www.areweembeddedyet.com/>

It currently redirects to:

* <https://rust-embedded.org>

Which doesn't really contain anything other than a link to <https://github.com/rust-embedded>.

(via <https://github.com/rust-embedded/wg/issues/15>)

Then the Rust Embedded workgroup provides: - Direction on how to using generics and zero-sized types to achieve functional safety - svd2rust, which provides safe abstractions to peripheral access from SVD files and achieves this functional safety - The embedded HAL spec, which makes porting to different vendors/hardware easy - Peripheral access controllers and HALs for various vendors & hardware

The Rust Embedded Devices Working Group curates a list of useful embedded Rust resources, including Peripheral Access Crates (autogenerated from SVD files), embedded-hal Implementation Crates (hand-written libraries implementing the traits (interfaces) specified by the embedded-hal), and Board Support Crates.

You should also look at https://github.com/rust-embedded/wg/issues/41 and https://github.com/rust-lang/rust/pull/55011#issuecomment-429336055.

Here's an interesting discussion, consolidated here. My view is you should use a restricted scope atomic (as best as can be supported) and interact with that through a handler struct. I.e. no global state.

Most of the issues are explained in EWG RFC 419. The TL;DR is that some resources need to implement Send to be usable from interrupts, but they must not be sent across cores.

thanks. looked that up. for the curious: https://embassy.dev/

Running the Embassy RP2040 USB CDC ACM serial example takes about 5 seconds on a Pico.

https://github.com/embassy-rs/embassy/blob/main/examples/rp/...

Async solves different problems, you can, for instance, have just a single-threaded CPU and still have a nice API if you have async-await. It might not be so cool at a higher level as Go's approach of channels and threads, but it's cool in embedded, read this:

https://github.com/embassy-rs/embassy?tab=readme-ov-file#rus...

"Rust's async/await 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 faster and smaller than one!"

I'm just toying with Raspberry Pi Pico and it's pretty nice.

Go and Rust have different use cases, the async-await is nice at a low level.

I have not yet dipped by toes in the Rust waters, but reading about the embassy project is actually what piqued my curiosity about using C++ coroutines in embedded. Are you familiar with the project or have you found it lacking?

I think I get the basics (shoutout to the Rust Embedded Working Group!), and I've started looking for the stack I'd be using. I think Embassy is really amazing, as well as the work of the ESP team -- hats off.

> }

And this is how to do it using embassy, which is an async framework for embedded in rust:

https://github.com/embassy-rs/embassy/blob/main/examples/rp/...

> not good for embedded

embassy begs to differ

https://embassy.dev/

async/await is really just a syntax for building state machines in a way that resembles regular code. It's compiled down to the same code that you would write by hand anyway (early on it had some bloat in state size but I think it's all fixed now).

And embedded has a lot of state machines!

You can run multiple executors at different interrupt priority levels (with multiple tasks per executor), which allows tasks on the higher priority executor to interrupt other tasks. Here's an example https://github.com/embassy-rs/embassy/blob/main/examples/nrf...