• From Zero to main(): Demystifying Firmware Linker Scripts

    Last time, we talked about bootstrapping a C environment on an MCU before invoking our main function. One thing we took for granted was the fact that functions and data end up in the right place in our binary. Today, we’re going to dig into how that happens by learning about memory regions and linker scripts.

  • Code Size Optimization: Measure Twice, Cut Once

    Every firmware engineer has run out of code space at some point or another. Whether they are trying to cram in another feature, or to make enough space for A/B firmware updates more code space is always better.

    In this series of posts, we’ll explore ways to save code space and ways not to do it. We will cover compiler options, coding style, logging, as well as desperate hacks when all you need is another 24 bytes.

    But first, let’s talk about measuring code size.

  • GNU Build IDs for Firmware

    In this post, we demonstrate how to use the GNU Build ID to uniquely identify a build. We explain what the GNU build ID is, how it is enabled, and how it is used in a firmware context.

  • Debugging Firmware with GDB

    If I had to choose one significant aspect that I was not aware of before starting my career as a firmware developer, it would be how much time is spent not actually developing, and instead debugging firmware!

  • From Zero to main(): Bare metal C

    Throughout the Zero to main() series of posts, we demystify what happens between when power is applied and your main function is called. In the process, we’ll learn how to bootstrap a C environment, implement a bootloader, relocate code, and more!

  • Programming the ATSAMD21 with IBDAP

    In the process of porting a blog post from the retired Arduino M0 Pro to Adafruit’s excellent Metro M0 Express, I ran into a few issues and scant amount of documentation. I’m writing this for the next poor soul wrestling with these systems.