This book uses an example project to illustrate each of the steps used to develop a new embedded system program.

System requirements and architecture are provided, followed by methods to estimate level of effort needed to implement them. A simple design methodology shows how to divide the system into cooperating virtual software objects, along with suggestions for their verification. Suggestions are made for coding, debugging, and verifying the virtual objects, as well as integrating them into a working program, and demonstrating the requirements have been met.

Complete source code, developed with the VSCode build environment, is an included extra with the purchase of this ebook.  The source code extra is found by clicking the extras button at the bottom of the menu found in the bottom half of your book's Library page on leanpub.

The source code implements a digital trombone, which uses a slide potentiometer to control note frequency, and an air pressure sensor with a tube into which the user blows to make notes and modulate their volume. A spring-loaded on-off switch is used to choose between saw, square, triangle, or sine waveforms. The interrupt driven, buffered DAC output is conveyed to an on-board, 3.5 mm audio jack.

The example program can be built with a free version of the GNU ARM compiler toolset on Windows, Linux, or Mac. The binary code produced can be copied to the NUCLEO-L432KC mbed icon on the desktop. Or the Visual Studio Code program from Microsoft may be used to build, load and debug the program on the target board.

Once you have a schematic, an eval board, and a set of requirements, you are ready to begin design of your embedded software system. This ebook demonstrates a topdown architecture technique, helps with the choice of runtime pattern, and develops module interaction diagrams for the example system. It reveals how a finished design emerges from the repeated interaction between architecture studies, module interaction analysis, and code prototyping. Readily available hardware is pictured and code libraries shown which allow the reader to build, and debug their own version of the example project.

Embedded software source code is synthesized from a variety of sources, including:

* original code written fresh for the new system

* compiler or chip vendor library code or examples

* integrated development environment examples

* examples from Github, and SourceForge, or other on-line sites

* code from previous product generations, possibly written for another processor and compiler

All this code cannot just be tossed into a blender and mixed to a smooth consistency.

Somebody has to select existing source code, and make sure it is ok to use. Then he must modify, organize, and package it into objects compatible with the system hardware. Lastly, more software objects must be defined to tie it all together; and meet the system requirements.

This organizational effort is called embedded software architecture.