embedded-rust

Embedded Rust

Purpose

Guide agents through embedded Rust development: flashing and debugging with probe-rs/cargo-embed, structured logging with defmt, the RTIC concurrency framework, cortex-m-rt startup, no_std configuration, and panic handler selection.

Triggers

• "How do I flash my Rust firmware to an MCU?"
• "How do I debug my embedded Rust program?"
• "How do I use defmt for logging in embedded Rust?"
• "How do I use RTIC for interrupt-driven concurrency?"
• "What does #![no_std] #![no_main] mean for embedded Rust?"
• "How do I handle panics in no_std embedded Rust?"

Workflow

1. Project setup

# Cargo.toml
[package]
name = "my-firmware"
version = "0.1.0"
edition = "2021"

[dependencies]
cortex-m = { version = "0.7", features = ["critical-section-single-core"] }
cortex-m-rt = "0.7"
defmt = "0.3"
defmt-rtt = "0.4"
panic-probe = { version = "0.3", features = ["print-defmt"] }

# Embassy (async embedded) — alternative to RTIC
# embassy-executor = { version = "0.5", features = ["arch-cortex-m"] }

[profile.release]
opt-level = "s"       # size optimization for embedded
lto = true
codegen-units = 1
debug = true          # keep debug info for defmt/probe-rs

# .cargo/config.toml
[build]
target = "thumbv7em-none-eabihf"    # Cortex-M4F / M7

[target.thumbv7em-none-eabihf]
runner = "probe-rs run --chip STM32F411CEUx"    # auto-run after build
rustflags = ["-C", "link-arg=-Tlink.x"]         # cortex-m-rt linker script

2. Minimal bare-metal program

// src/main.rs
#![no_std]
#![no_main]

use cortex_m_rt::entry;
use defmt::info;
use defmt_rtt as _;      // RTT transport for defmt
use panic_probe as _;    // panic handler that prints via defmt

#[entry]
fn main() -> ! {
    info!("Booting up!");

    // Access peripherals via PAC or HAL
    let _core = cortex_m::Peripherals::take().unwrap();
    // let dp = stm32f4xx_hal::pac::Peripherals::take().unwrap();

    loop {
        info!("Running...");
        cortex_m::asm::delay(8_000_000);  // rough delay
    }
}