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A Matter Wi-Fi Light Bulb in Rust on the Raspberry Pi Pico 2 W
- melastmohican 4mo agoHi HN, I’ve been experimenting with the new Raspberry Pi Pico 2 W (RP2350) and wanted to see how difficult it would be to build a fully compliant Matter smart device from scratch using Rust. I put together a complete "Blinky" example using the rs-matter stack and the embassy async framework. It uses BLE for the initial commissioning phase and Wi-Fi for network connectivity. Once flashed, you can provision it directly into Apple Home, Google Home, or Home Assistant using your smartphone—no cloud accounts required. It exposes a standard Matter On/Off cluster that toggles a physical LED wired to the GPIO pins. A few interesting technical notes from the build: Bare Metal: It runs entirely no_std on bare metal using embassy-rp. Radio Coexistence: Getting the CYW43439 wireless chip to handle concurrent BLE (for commissioning) and Wi-Fi (for Matter IP traffic) on the RP2350 took some tweaking. We actually had to dial back the PIO SPI clock divider specifically because the RP2350's faster 150MHz core clock was causing bus corruption when the radio was saturated! Async Rust: The repo includes the full async CoEx (coexistence) runner setup to safely multiplex the radio between the Bluetooth and Wi-Fi stacks concurrently. If you’ve been wanting to build local-only smart home devices but felt intimidated by the massive official C++ Matter SDK, doing it in Rust is actually becoming incredibly approachable. Would love to hear if anyone else is building custom smart home gear in Rust.
- DazWilkin 4mo agoThis looks very interesting. Thanks for sharing!
- MrBuddyCasino 4mo ago> bus corruption when the radio was saturated How do you even diagnose this?
- melastmohican 4mo agoThe initial approach was to run BLE and Wi-Fi simultaneously. Provisioning sometimes worked. It seems like there was some interference. Then switched to run BLE with Wi-FI off. When I got Wi-Fi credentials, switched BLE off, and turned Wi-Fi on. It still had some issues. Turned out when slowed down SPI bus, it started working. Only tested with Home Assistant and have to fork and patch rs-matter-embassy
- mrlambchop 4mo agore: wifi/ble together That sounds like the crate didn't have coexistence enabled or the defaults were really odd - so much boring stuff to write about BLE/WiFi Coex, but the short is "the default settings" are pretty good for low bandwidth IoT devices. I'll peek at the code out of interest :)
- mschuster91 4mo agoWhat OP says > Turned out when slowed down SPI bus, it started working. reeks of either RF interference issues or power rail issues. Power is not the strongest domain of anything RPi so that's where I'd look first.
- taneq 4mo agoUse a digital storage scope, many of them can directly decode protocols like SPI . Then a lot of trial and error to figure out when exactly the issue happens and what else is happening around that time.
- jkwang 4mo agoRust on embedded is becoming more approachable with Embassy and the Pico SDK. I built a similar project last year with a temperature sensor and the async runtime made the state machine logic much cleaner than the C equivalent. Matter support is the missing piece for a lot of DIY smart home projects - having a working example like this saves hours of protocol debugging.
- LoganDark 4mo agoLanguages: 75.4% Linker Script 18.2% Rust 6.4% Shell About sums up embedded development in Rust.
- nevi-me 4mo agoMost of the code is already in libraries. rs-matter includes a lot of batteries, so for simple clusters you end up writing little code.
- mkj 4mo agoIt looks like github is just buggy in this case.
- sli 4mo agoWell all of the linker script is just two standard memory map files, one for the 2040 and one for the 2350, so really it suggests that this needed very little code to make this work. The 6.4% shell represents a shebang line, two comments, and a single `set -e` call, after all.
- kibwen 4mo agoThere's nothing about embedded development in Rust that would make it more reliant on linker scripts than any other language. Github's count is misleading here.
- bschwindHN 4mo agoHere are the line counts: rust-rpico2-embassy-examples $ tokei . ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Language Files Lines Code Comments Blanks ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Alex 2 330 280 0 50 Shell 1 25 13 3 9 TOML 2 76 58 7 11 ───────────────────────────────────────────────────────────────────────────────── Markdown 1 254 0 181 73 |- BASH 1 8 8 0 0 |- Shell 1 1 1 0 0 (Total) 263 9 181 73 ───────────────────────────────────────────────────────────────────────────────── Rust 10 1256 937 86 233 |- Markdown 10 340 8 263 69 (Total) 1596 945 349 302 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Total 16 2290 1305 540 445 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ I guess "Alex" would be the linker scripts ending in .x?
- teaearlgraycold 4mo agoI love the Pico product line and think they are severely underutilized. Many Pi 3/4/5 projects can be performed with one of these little guys. Don’t chain yourself to a whole Linux distro unless you really need it.
- zxexz 4mo agoWhat I'll never understand about this whole thing is why most people seem to easily tolerate the rigamarole of maintaining an entire host SBC OS and sending or even cross compiling binaries to it, for microprocessor work. I much prefer maintaining a dev env on machine(s) and sending and flashing a binary over the wire. Maybe I just dislike state, but the pico (and several other MCU ecosystems these days) make it so easy to
- teaearlgraycold 4mo agoI'm sure you're aware, but for the record the Pico has state. That's one of the best things about it. You have a very fully featured Python environment (or rust, or C) with a read/write filesystem. The WiFi SDK is also super useful. They can make HTTP requests (and HTTPS without full CA validation), host an HTTP server, even host an access point.
- ssl-3 4mo agoThe advantage is familiarity, I think. Like: I suck at code. But I've known how to walk around in *nix systems and use things like bash to chain together commands like awk, grep, and sed for ~30 years. Maybe I'd even toss in some badly-cooked perl or python (or both!), when that seemed necessary. For a very long time, I've been able to get some things done, but my skillset was focused on doing these things with real computers with live filesystems and real user interfaces, not MCUs. So, some years ago: When I wanted to turn a window fan on and off based on some network-retrieved weather conditions, I didn't even consider an MCU. I didn't want to learn a new way of doing things; I just wanted a computer to get some data and decide whether to turn the fan on and off. And I wanted that done sooner instead of later. I accomplished this with a Raspberry Pi Zero W -- with the whole OS. I didn't cross-compile anything. I didn't have to target some weird-looking external environment, or learn a new way of doing things. Setting up the dev environment was very familiar: Dump a binary onto an SD card, boot it, get it onto the network, and use it. I just SSH'd into that tiny little computer like I would any other Linux box and wrote my stupid little cobbled-up scripts right there, in-situ, on the final device that would be performing the work -- with a familiar interactive shell. The end result worked very well. I'm not ashamed of any of this at all. --- Later, I switched from networked weather reports to an RTL-SDR dongle and software decoding to listen for over-the-air broadcast reports from someone else's nearby APRS weather station, and used that as a source of weather data instead. Can we even get that done in MCU land? (Should we even try to do so for just one window fan?)
- fundatus 4mo agoThink about Matter what you want, but the fact that it is simply IP-based so you can hack something like this together is pretty amazing.
- stavros 4mo agoI don't know, I think the downsides outweigh the benefits. I don't want to have to secure a bunch more IP-based devices that can talk to my computers. I'd rather they were separated at the radio level, like Zigbee.
- psyonity 4mo agoMatter is just the protocol from my understanding, it can also be used over Thread, which is a seperate radio and made to replace Zigbee/Z-Wave.
- stavros 4mo agoYes, this is true, but I think over Thread it's also fairly complicated, as a protocol. I'm not very familiar with it, though, admittedly.
- comfydragon 4mo agoThread is also IP(v6)-based. But in this context, Thread would go a fair ways toward solving stavros's concern, as it means security could be enforced on the Border Router(s), rather than each individual device.
- BluSyn 4mo agoRust on embedded is fun to play with. Few years ago I made a custom RGB LED rope light controller using ESP32 C3 DevKit and Rust embedded, connecting light to homeassistant via MQTT auto discovery. Was surprisingly easy to get started as someone who had limited experience with embedded programming, and only hobby Rust experience. But the supported hardware in Rust crates was limited at the time and C3 dev kits weren’t widely available, so I never used it for anything. HAL support has only gotten better since then. I may try to resurrect that project now with Pico 2 and Matter.
- melastmohican 4mo agoI was playing with the official Espressif Rust Board, which is ESP32C3, but I didn't try Matter on it. It would be on the same boat as Pico W because it only supports Matter over Wifi. https://github.com/melastmohican/esp-rust-board-discovery https://github.com/melastmohican/esp-rust-board-discovery Now I would try something like ESP32C6 with Thread support: https://github.com/melastmohican/adafruit-feather-esp32c6-embassy-examples/blob/main/examples/matter_thread_light.rs https://github.com/melastmohican/adafruit-feather-esp32c6-em...
- anya53 4mo ago[dead]
- rdsubhas 4mo agoCool project! Just one thing: It says "ultra low" power. But ultra low is not necessarily the same as battery powered, which itself doesn't necessarily mean coin-cell battery powered. My experience with wifi modules I've built so far has been, they've all been "low" but not usually battery powerable. I wish the README provides more info whether it's suitable for battery-powered operation, and if so how which.
- surajrmal 4mo agoNothing with WiFi will ever be coin cell battery powered. But that doesn't mean it couldn't be battery powered for a year or longer with bigger batteries. Otherwise you'll need a different radio technology.
- happyopossum 4mo ago> Nothing with WiFi will ever be coin cell battery powered. Well, except for all the coin cell operated matter over WiFi smart buttons / remotes / switches you can buy from just about anywhere…
- surajrmal 4mo agoNone of those are using WiFi. Most use a different radio technology and require a hub to bridge the network.
- solid_fuel 4mo agoI think some do use regular wifi, especially the amazon ones, but with a button you have an advantage where you could just stay idle and off the network most of the time, and only connect to send an event when pressed.
- everforward 4mo agoThat likely increases your latency by a fair bit. Most of my devices take a second-ish to connect, configure the WiFi stack and start sending data. I’m not sure I’d want a full second of latency on button presses. I would have figured Amazon used BTLE to the Alexa and used it as a BT to WiFi gateway
- ryanshrott 4mo ago[dead]
- bleepblap 4mo agoI'm desperate for people to make tech that's searchable. I'd like to figure out some of the thread/matter bits for my own projects and this is terribly annoying to do
- RA2lover 4mo agoThread isn't interested in hobbyists. https://news.ycombinator.com/item?id=40326269 https://news.ycombinator.com/item?id=40326269
- bleepblap 4mo agoThanks for the post. :( I had some ideas for little projects to mess around with and thought thread would've been something interesting to learn..
- melastmohican 4mo agoActually, you can make it work with Arduino Nano Matter. It boils down to vendor support. If they support Arduino like Silicon Labs or Espressif, then it is available for hobbyists.