Two boards on the same Wi-Fi should be able to talk to each other without a cloud server in the middle, yet most hobby projects still route everything through one. A Rust networking library called iroh now runs on the RP2350, the chip inside the Raspberry Pi Pico 2, and that changes what a classroom sensor network can look like.
Why a mesh on a microcontroller matters
iroh is a modular Rust networking stack that opens direct, encrypted connections between devices, apps, and cloud instances. It can ride on Wi-Fi or cellular, and on links that are not IP-based at all, such as Bluetooth LE and LoRa. For a school project, that means a node in the robotics lab and a node in the greenhouse can find each other without port forwarding or a rented server. The announcement on the Raspberry Pi news page credits the iroh team with the port.
What was actually built
The iroh developers demoed the stack on Pimoroni’s Presto, an RP2350 board with Wi-Fi and a touchscreen, and also on a plain Pico 2 with no radio. Wireless on these boards comes from the Raspberry Pi Radio Module 2, which packs the same Infineon CYW43439 chip found on the Pico W and Pico 2 W. That chip handles 2.4 GHz Wi-Fi and Bluetooth, so one radio covers both transports.
Technical details worth knowing
The RP2350 has 520 KB of SRAM and two cores running up to 150 MHz, which is tight for a full networking stack. Rüdiger Klaehn’s engineering write-up, linked from the announcement, describes the workarounds needed to fit iroh into that memory budget. Expect the usual gotchas on a microcontroller: keep allocations small, avoid blocking calls on the core handling the radio, and watch stack depth when you add crypto. The examples live in the iroh-pico-examples repository, so you can read working code before writing your own.
Build it yourself
Start with a Pico 2 W and a USB cable, flash one of the repository examples, and confirm two boards connect to each other. Then add an I2C sensor such as a BME280 on SDA and SCL with 4.7k pull-up resistors if your breakout lacks them, and send readings from one node to the other. For a thesis on distributed sensing, compare this against an MQTT broker setup and measure latency with 3 or 4 nodes. Check Pico 2 W stock and breadboard parts at Circuit.Rocks before you start.
Frequently Asked Questions
What is iroh and what does it do on the RP2350?
iroh is a modular Rust networking stack that creates direct, encrypted connections between devices over Wi-Fi, cellular, Bluetooth LE, or LoRa. It now runs on the RP2350, including the Pico 2 and Pimoroni Presto.
What hardware do I need to try it?
A Raspberry Pi Pico 2 W or a Pimoroni Presto is enough, since both pair the RP2350 with the CYW43439 radio. Start from the iroh-pico-examples repository on GitHub.
What will I learn if I build this?
You will learn peer-to-peer networking basics, embedded Rust workflow, memory budgeting on a 520 KB SRAM chip, and how to wire I2C sensors for a distributed monitoring project.
