• Building a CLI for Firmware Projects using Invoke

    Building a small (or large) command line interface (CLI) for a project is a great way to get an entire team to build, test, debug, and work with a project in the same way using the same set of tools. This post goes into detail about how to think about a project’s CLI and implementing one using the Invoke Python package.

  • Code Size Optimization: GCC Compiler Flags

    In this post, we will review compiler options that we can use to reduce firmware code size. We will focus on arm-none-eabi-gcc, the GCC compiler used for ARM-based microcontrollers, though most of the compile-time flags we will cover are available in other GCC flavors as well as in Clang.

  • From Zero to main(): How to Write a Bootloader from Scratch

    In this post, we will explain why you may want a bootloader, how to implement one, and cover a few advanced techniques you may use to make your bootloader more useful.

  • A Deep Dive into ARM Cortex-M Debug Interfaces

    In this article we will walk up through the hardware and software stack that enables debugging on ARM Cortex-M devices, demystify what is actually happening and go through a step-by-step example, tracing a basic debugger operation end to end using a logic analyzer.

  • Bluetooth Low Energy: A Primer

    In today’s post, we will be covering one of the most popular low-power IoT technologies: Bluetooth Low Energy (BLE). We will give an overview of how BLE works, dig into each protocol layer, and walk you through an example setting up BLE on a Nordic nRF52 microcontroller.

  • Using Python PyPi Packages within GDB/LLDB

    In a previous post, we discussed how to automate some of the more tedious parts of debugging firmware using Python in GDB Scripts. To make these commands more powerful, one could use third-party packages from Python’s PyPi repository. In this post, we will discuss how to properly setup GDB, Python, and optionally virtualenv and then modify the uuid_list_dump command from the post mentioned above to make use of a third party package installed through PyPi.

  • Fix Bugs and Secure Firmware with the MPU

    Many ARM MCUs implement an optional unit, known as the Memory Protection Unit (MPU), which lets you control how regions of memory are accessed. In this article, we will deep dive into the unit and walk through a few practical examples of how it can be used to prevent bad memory accesses and security exploits on Cortex-M devices.

  • Get the most out of the linker map file

    In this article, I want to highlight how simple linker map files are and how much they can teach you about the program you are working on.