Rust STM32F4 Bootloader

A robust, multi-stage bootloader system for STM32F4 microcontrollers implemented in Rust. This project demonstrates firmware validation, secure update mechanisms, and memory management using Rust's safety features for embedded development.

The system implements a structured four-component bootloader architecture:

• Boot (16KB): First-stage bootloader that validates and loads either Loader or Updater
• Loader (16KB): Main bootloader with XMODEM update capability for Application and Updater
• Updater (16KB): Similar to Loader but can also update the Loader itself
• Application (384KB): The user firmware that runs the actual application

Each component features a structured header (0x200 bytes) containing metadata such as magic number, version, CRC checksum, and vector table address. The system implements a comprehensive set of validation mechanisms at each stage to prevent corrupted firmware from executing.

Project Goal: This implementation leverages Rust's memory safety features and ownership model to create a more reliable and secure bootloader, minimizing the risk of memory corruption and other common embedded programming errors.

Bootloader Flow

The bootloader consists of four components with a secure chain of trust and multiple paths for normal operation and updates:

The bootloader uses a carefully desided memory layout for its components:

Each firmware component includes a 512-byte header with the following structure:

// Rust header structure for firmware components
#[repr(C, packed)]
pub struct ImageHeader {
    pub image_magic: u32,
    pub image_hdr_version: u16,
    pub image_type: u8,
    pub is_reserved: u8,
    pub version_major: u8,
    pub version_minor: u8,
    pub version_patch: u8,
    pub _padding: u8,
    pub vector_addr: u32,
    pub crc: u32,
    pub data_size: u32,
    pub reserved: [u8; 0x1E0],
}

Each bootloader component is identified by a unique magic number:

• Loader: 0xDEADC0DE
• Updater: 0xFEEDFACE
• Application: 0xC0FFEE00

The project is organized into multiple Rust crates:

├── boot/                  # First-stage bootloader
├── loader/                # Main bootloader
├── updater/               # Updater bootloader
├── application/           # Example application
├── stm32f4/               # STM32F4 peripheral access crate
├── misc/                  # Shared library components
│   ├── src/
│   │   ├── bootloader.rs  # Common boot code
│   │   ├── flash.rs       # Flash memory operations
│   │   ├── image.rs       # Firmware image definitions
│   │   ├── ring_buffer.rs # UART buffer implementation
│   │   ├── systick.rs     # System tick utilities
│   │   └── xmodem.rs      # XMODEM protocol implementation
├── scripts/               # Build and utility scripts
└── build.ps1              # Main build script