Rust on the ESP32 (2019)

https://mabez.dev/blog/posts/esp32-rust/

by lnyan • 6 years ago

133 44 6 years ago

Follow up post https://mabez.dev/blog/posts/esp32-rust-svd-pac/

bborud4• 6 years ago

I would really love to see more interest in Rust from the embedded industry. With the influx of new developers into embedded programming I think there is an opportunity.

weinzierl4• 6 years ago

Yes, especially when Rust could be a relief to many pains embedded software suffers from. The counter argument is of course that embedded software is very entrenched. Often we would be happy if we could use a normal C++ compiler like gcc or clang instead of the fragile pieces of art that semiconductor manufacturers give us.

bborud4• 6 years ago

I think the embedded world needs a bit of outside blood. Being able to replace C/C++ with something a bit more conducive to helping people develop correct code would be a great plus. But the tooling also needs some help. Good tooling that isn't a nightmare to set up and maintain is crucial.

steveklabnik2• 6 years ago

One of the Rust-focused consultancies does a lot of embedded. There’s a whole rust + embedded specific conference now. It is a huge space, but some stuff is certainly being done!

pjmlp4• 6 years ago

Even C needs more love from the embedded industry, given how many still use C89 dialects, even if the tooling might already support something better, let alone languages that attempt to replace C.

Leherenn2• 6 years ago

C versions after 89 doesn't bring much to be honest. So either you want more than what C can offer you, and usually the option is C++, or you're fine with what you have.

ktrl• 6 years ago

One roadblock is that many in the embedded software industry uses proprietary IDEs and tools like Keil, Atmel Studio, CCStudio and STM32CubeIDE. These propietary IDEs and tools are often based on Eclipse or Visual Studio Isolated Shell.

How good is the Rust support in Eclipse and Visual Studio?

Visual Studio should not be confused with Visual Studio Code. The latter has great Rust support.

nicoburns• 6 years ago

Wouldn't escaping this proprietary tooling be one of the big benefits of switching to Rust?

steveklabnik2• 6 years ago

Eclipse had a plugin that IIRC was supported by the foundation, but I’ve never used it.

detaro• 6 years ago

I'm actually positively surprised how well that field develops, compared to how slow it usually operates.

Also, "embedded" is a massive field with very different cultures and needs.

StavrosK3• 6 years ago

Does anyone know what the situation with Rust on the NRF is? It's all so new that there's no "getting started" guide, but even figuring out which repos to check out is hard.

dutchmartin• 6 years ago

There are crates for that [1]. But if you are new to rust and embedded, I would recommend to read through the rust embedded book [2] and practice with the stm32 board.

[1] https://github.com/nrf-rs/nrf-hal

[2] https://rust-embedded.github.io/book/

StavrosK3• 6 years ago

Ah, thanks. I'm not new to embedded, just to Rust on embedded. STM32s are a bit too overpowered for me, I usually use ESP8266s, that's why I thought the NRF might be a good bet (and better supported by Rust).

Avamander• 6 years ago

I recommend you check out the PineTime project and Lup Yuen Lee's tutorials. It might give a nice starting point.

https://github.com/lupyuen/pinetime-rust-mynewt

https://medium.com/swlh/sneak-peek-of-pinetime-smart-watch-a...

StavrosK3• 6 years ago

That's fantastic, thank you!

rkachowski• 6 years ago

would this presumably also run on the esp8266?

swsieber• 6 years ago

Yes, though IIRC a recent release broke esp8266 support accidentally. I haven't checked back to see if it's working again.

rbtying2• 6 years ago

The compiler toolchain can cross compile to esp8266, but I think the pure Rust HAL is less developed there. If you use Rust to write components/code that link against the ESP-IDF, I’d imagine that would work?

I have the toolchain in a Docker container if you want to try it out.

rbtying2• 6 years ago

I’ve been playing with Rust on the ESP32 using these tools on and off over the last couple of months or so, relying more in linking to the existing FreeRTOS/C HAL for accessing the peripherals.

One thing I haven’t quite figured out: a substantial number of onboard features are configurable at image build time, which then change the effective C libraries via preprocessor definitions. So, it doesn’t quite work to naively run bindgen on the header file once, and then embed that in a -sys crate and put it on crates.io

I think you can hand craft a -sys crate with all the appropriate config options as cargo features, but that seems both very time-consuming and likely to drift from the newest esp-idf versions. The alternative of running bindgen periodically (e.g. as part of the build process) works fine for one project, but then how do you publish reusable libraries online?

MrBuddyCasino3• 6 years ago

The ESP32 API surface is huge, and the libraries have many configuration settings. Rust-ifying this is a huge endeavour. One way could be to just interface with the vendor HAL using Rust wrapper, but doing that in a safe way that respects the lifetime rules can't be easy? Also AFAIK some lower level radio APIs are locked and hidden behind a binary blob, so the ESP32 can't be misused as a jammer.

Its very tempting to try this due to the huge amount of resources the hardware has, but it is a huge amount of work. Just being able to access the registers isn't very valuable, the ESP is about Wifi, BT and I2S. If there are no ergonomic Rust APIs for those, why even bother?

elcritch2• 6 years ago

It's true and a bit surprising how much of the ESP32's API's are configurable or change based on config options. Espressif has built an impressive amount of functionality on top of FreeRTOS. It'd be nice to see Rust more widely adopted, but it seems to require an entirely rewritten SDK as so much of the API are C macros and defines.

Given that I decided to go a middle ground and use Nim with its new ARC (GC reference counting and move semantics). In theory it's less efficient than compile time Rust memory management but it works well in practice. Wrapping the C API is trivial and handles all of the C defines as well as writing in C, since it compiles down to it. And you can use any Nim or C libraries. It's surprisingly effective!

Except you still get data races from the C API's which Rust would likely help prevent. So it's cool to see someone toying with an xtensa llvm backend. I wish LLVM still fully supported a C backend so you could compile Rust to C and build that. Hopefully in the long run, more native rust libraries will exist for more full functionality embedded.

ncrmro• 6 years ago

Was learning a lot of rust and now c and Mabez and everyone else is really helpful on the esp-rs matrix channel.

muska32• 6 years ago

There's also this guide https://rust-embedded.github.io/book/

Although, I'm more interested in learning STM32 development, due to recommendations that it is far superior to ESP32 boards. Anyone have some tips on how to get started on this front as a hobby?

mdtusz• 6 years ago

I ordered one of the STM32 development boards when this was first published. It's fairly straightforwards to get basic blinky demos working, but it was about at this point that I ran out of steam, and you're basically left to fend for yourself, implementing anything more complex from scratch.

It may have changed since, but rust embedded definitely isn't hobbyist friendly unless the goal is to make things work, rather than to just make things.

muska32• 6 years ago

Right, that's ultimately what I am worried about.

jolmg• 6 years ago

Lol. I was expecting the article to be about how to clean up metal corrosion from the terminals of an ESP32 chip.

Rust on the ESP32 (2019)

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