Writing software in C, as well as in every compiled language, requires the code to be transformed to an executable format for a specific target to run it. C is portable across different architectures and execution environments. Programmers rely on a set of tools to compile, link, execute, and debug software to a specific target.

Building the firmware image of an embedded system relies on a similar set of tools, which can produce firmware images for specific targets, called a toolchain. This section gives an overview of the common sets of tools required to write software in C and produce programs that are directly executable on the machine that compiled them. The workflow must then be extended and adapted to integrate the toolchain components, and produce executable code for the target platform.

An embedded toolchain is a set of software tools aimed to build software for a specific platform. While, in some cases, the complexity of the toolchain can be abstracted through a GUI, it is often distributed as a set of standalone applications, each one serving a specific purpose. Understanding the single tools and learning how to use them properly speeds up the development process and gives us a closer look at how things work under the hood.

GCC is nowadays one of the reference toolchains to build embedded systems, due to its modular structure allowing backends for multiple architectures. Thanks to its open source model, and the flexibility in building tailored toolchains from it, GCC-based toolchains are among the most popular development tools in embedded systems.

Building software using a command-line-based toolchain has several advantages, including the...

For development purposes, embedded platforms are usually accessed through a JTAG or an SWD interface. Through these communication channels, it is possible to upload the software onto the flash of the target, and access the on-chip debug functionalities. There are several self-contained JTAG/SWD adapters on the market that can be controlled through USB from the host, while some development boards are equipped with an extra chip controlling the JTAG channel, that connects to the host through USB.

A powerful generic open source tool to access JTAG/SWD functionalities on the target is the Open On-Chip Debugger (OpenOCD). Once properly configured, it creates local sockets that can be used as a command console and for the interaction with the debugger frontend. Some development boards are distributed with additional interfaces to communicate with the core...

Debugging alone, or even simple output analysis, is often not enough when verifying system behavior and identifying issues and unwanted effects in the code. Different approaches may be taken to validate the implementation of the single components, as well as the behavior of the entire system under different conditions. While, in some cases, the results can be directly measurable from the host machine, in more specific contexts, it is often difficult to reproduce the exact scenario, or to acquire the necessary information from the system output.

External tools may come in handy, especially in the analysis of communication interfaces and network devices in a more complex, distributed system. In other cases, single modules can be tested off-target using simulated or emulated environments to run smaller portions of the code base.

Different tests, validation strategies,...

This chapter introduced the tools for working on the development of embedded systems. A hands-on approach has been proposed, to get the reader up and running with the toolchain and the utilities required to communicate with the hardware platform. Using appropriate tools can make embedded development easier and shorten the workflow iterations.

In the next chapter, we provide indications on the organization of the workflow when working with larger teams. Based on real-life experiences, we propose solutions for splitting and organizing tasks, executing tests, iterating throughout the phases of design, and the definition and implementation of an embedded project.