Yes I wonder what was wrong with the C code. Was it fixable, was it just a single loop code that ran or could they have used something like FreeRTOS to handle multiple tasks with less chance of bugs?

I would have liked to have more details because it's easy to have memory related issues when using a serial protocol in a memory constrained environment and I was wondering if somehow some feature of Rust helped them.

I would guess that the more expressive type system is very nice but I don't expect memory safery features to be that useful in this context. Would like to hear from someone with real world experience on that.

If you're parsing a serial protocol on an embedded system where you're only getting a byte-at-a-time (from a register), or possibly up to 8 at a time, then a parser combinator library such as nom should make it very easy to create a bulletproof parser.

Definitely much easier than in C, where I've resorted to using Ragel for safely parsing serial protocols (and also in Go!) since it generates a single small dependency free source file containing the state machine and your "actions", but nom is much more expressive.

Deeply doubt so.

Parser combinators are notoriously poor performance and memory-wise. They are somewhat nice to write if you like the style and don’t mind the tax but we are talking about ESP32 here.

Unless they are inexperienced, the issue is unlikely to be the state machine anyway and more likely to be in how they manage buffering of long message to avoid running out of RAM.

I was just about to point this out in my own comment but yours sums it up quite nicely. As an embedded software guy this article gives next to no specifics or details on what the bugs were and how they got solved with Rust.

Some more information on ESP32 on Rust. Espressif (the organisation behind ESP32) spent effort to properly support Rust on their chips, see their documentation: https://docs.esp-rs.org/book/

Another nice resource for Rust embedded is https://embassy.dev/ which also supports STM32, Nordic chips, and RP2040.

IMO, the coolest feature about Rust embedded is that Async Rust works! This makes building a HTTP server for your embedded chip easy.

Most embedded code is pretty bad at async - that could be a game changer.