Work Environment and Workflow Optimization

The first step toward a successful software project is choosing the right tools. Embedded development requires a set of hardware and software instruments that make the developer’s life easier and may significantly improve productivity and cut down the total development time. This chapter provides a description of these tools and gives advice on how to use them to improve the workflow.

The first section gives us an overview of the workflow in native C programming, and gradually reveals the changes necessary to translate the model to an embedded development environment. The GCC toolchain, a set of development tools to build the embedded application, is introduced through the analysis of its components.

Finally, in the last two sections, strategies of interaction with the target are proposed, to provide mechanisms for the debugging and validation of the embedded software running on the platform.

The topics covered in this chapter...

Workflow overview

Writing software in C, as well as in every other compiled language, requires the code to be transformed into 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.

The C compiler

The C compiler is a tool responsible for translating source code into machine code, which can be interpreted by a specific CPU. Each compiler...

Text editors versus integrated environments

While mostly a matter of developer preferences, the debate is still open in the embedded community between those who use a standalone text editor and those who prefer to have all the components of the toolchain integrated into one GUI.

Modern IDEs incorporate tools for the following tasks:

• Managing the components of the project
• Quickly accessing all the files for editing as well as extensions to upload the software on the board
• Starting a debugging session with a single click

Microcontroller manufacturers often distribute their development kits along with IDEs that make it easy to access advanced features that are specific to the microcontroller, thanks to preconfigured setups and wizards facilitating the creation of new projects. Most IDEs include widgets to automatically generate the setup code for pin multiplexing for specific microcontrollers, starting from a graphical interface. Some of them even offer simulators...

The GCC toolchain

While in the case of the IDE, its complexity is abstracted through the user interface, a toolchain is a set of standalone software applications, each one serving a specific purpose.

GCC is 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 possibility of automating the intermediate steps that would build all the modules up from the source code into the final image. This is particularly useful when it is required to program multiple devices in a row or to automate builds on a continuous integration server.

ARM distributes the GNU Arm Embedded Toolchain for all the most popular development hosts. Toolchains...

Interacting with the target

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 functionality. Several self-contained JTAG/SWD adapters on the market can be controlled through a USB from the host, while some development boards are equipped with an extra chip controlling the JTAG channel that connects to the host through a 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 interaction with the debugger frontend. Some development boards are distributed with additional interfaces to communicate with the core CPU. For example, STMicroelectronics prototyping boards for Cortex-M are rarely shipped without a chip technology called ST...

Validation

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 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, and tools are considered in this section to provide solutions for any scenario.

Functional tests

Writing...

Summary

This chapter introduced the tools for working on the development of embedded systems. A hands-on approach has been proposed to get you 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 workflow iterations.

In the next chapter, we provide indications for workflow organization 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.