How To Develop Embedded Software
Last updated on 2017-07-29
About the Book
The source code in this book implements a digital theremin, using a resistive X-Y touch screen, and a five position joy-switch for input. Its output is an analog signal consisting of a selected audio waveform, modulated by an Attack-Decay-Sustain-Release envelope triggered and updated by a finger touching the resistive touch screen.
The X axis of the touchscreen controls volume, while the Y axis controls frequency. The joy-switch controls the hardness or softness of the attack phase, and the decay rate of the envelope after the finger is removed from the screen.
Waveforms supported include square, triangle, and saw; although the waveform generation algorithm supports arbitrary single cycle waveform templates.
A free version of the GNU ARM compiler was used under Windows 7 to build the system. Startup code and Linker script were supplied by the free IDE used to develop and debug the program. Those files are included in the source code section of the book.
A makefile is included which can build the debug or release versions of the code without using the IDE.
The book is intended to convey a useful point of view on embedded system development, which will help working programmers develop their software engineering skill set.
Requirements, system architecture, and complete design documentation make it easy to follow the source code, or to make changes and add features as needed.
A collection of verification and validation tests are described, which can be used to make sure source code changes have not broken any features of the program.
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