9. Converting a Rust Project to Bare-Metal Firmware | no_std, no_main, & panic_handler Explained

❤️ Support this series (optional): If you find these STM32 + Rust tutorials helpful and would like to support more embedded content, you can do so here: paypal.me/edwardpie Thank you for helping me continue creating free embedded systems tutorials! In this video, we take a regular Rust project and manually transform it into a bare-metal firmware project for STM32 ARM Cortex-M microcontrollers. Instead of relying on templates or project generators, you'll learn exactly what changes are required and why each one is necessary. We begin by removing Rust's dependency on the standard library with #![no_std], then replace the normal program entry point using #![no_main]. Finally, we implement a custom #[panic_handler] to satisfy the compiler when panics occur in a bare-metal environment. Along the way, we'll discuss why these attributes are required and how they allow firmware to run directly on hardware without an operating system. This is the ninth video in the STM32 + Rust series, where we continue building the foundation for embedded Rust development. Understanding these three components is a major milestone because nearly every bare-metal Rust firmware project will use them before adding startup code, peripherals, and hardware abstraction layers. By the end of this tutorial, you'll understand how to manually convert a standard Rust application into a bare-metal firmware project, why no_std, no_main, and panic_handler are essential, and how they prepare your code to run on STM32 ARM Cortex-M microcontrollers.