Introduction

FlintOS is a tiny real-time operating system for small 32-bit chips — the kind inside an ESP32 or a Raspberry Pi Pico. You write your app in plain Rust: start a task, blink an LED, read a sensor. FlintOS quietly handles the hard parts underneath — scheduling, timing, talking to the hardware.

The whole point

FlintOS is meant to be dead-simple to use. No build-system yak-shaving, no hundred-line startup dance, no fighting the borrow checker to turn on an LED. Pick a board, write a little Rust, flash it. That’s the bar we hold everything to.

What you get for free

Link the kernel into your app and all of this comes along — no extra crates, no setup. The point of each one is to save you the thing that usually goes wrong on a chip with no screen and no debugger attached.

🪵 Logging you can turn down

log_error! … log_trace!, with a build-time level. Keep chatty logs while you develop; a release build compiles the noise away so you pay nothing for it in the field.

📊 Metrics without the plumbing

Name a Counter or Gauge in a line and read it back live. Answer “how many, how often, how full?” without bolting on a framework.

🧯 Panic capture

When something crashes you get a snapshot — which task, where, and why — in debug builds, and a clean reset in release. A dead board on your desk becomes a readable report instead of a mystery.

📏 Stack high-water marks

See how close each task came to overflowing its stack. Size your stacks from real evidence instead of guessing and hoping.

⏱️ CPU load & timing

Per-task load and precise timing spans, off by default. Find the slow path with numbers — and pay nothing when you’re not looking.

Who it’s for

• App authors who want firmware in plain, readable Rust — spawn a task, open a bus, talk to a sensor — without wrestling the hardware.
• Driver & board authors adding new peripherals and boards, inside a layer model that keeps chip-specific code and portable code cleanly apart.

What runs today

FlintOS runs on two chip families right now, with a portable core that keeps the chip- and CPU-specific bits at the edges:

Xtensa LX6 · ESP32

• ESP32-DevKitC / WROOM-32 — the reference board
• ESP32-WROVER
• M5Stack Atom Matrix
• M5Stack Atom Lite
• M5Stack Core2 (bring-up)

Arm Cortex-M0+ · RP2040

• Raspberry Pi Pico
• Wio RP2040 Mini (both cores)

The full matrix, with what’s verified on hardware, is in Supported boards.

Where to start

PrerequisitesThe tools you need first, by operating system.

QuickstartBare toolchain to a running board in a few minutes.

Hello, worldWrite and flash your first app.

ArchitectureHow FlintOS is put together, and why.

Writing a driverAdd support for a new part.

API referenceEvery crate, generated from the source.