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.

This book documents and provides requirements, architecture, design, and source coed for a project to build a tracking device using GPS and a cell modem.

The software uses simple state machines to parse GPS NMEA sentences, and to interact with the on-board cell modem which exchanges text messages with the user's smart phone.

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 book. A makefile is included which can build the debug or release versions of the code without using the IDE.

Source code includes a FIFO manager to handle the interrupt-driven UART interfaces to GPS and cell modem. A time converter changes GPS UTC time into Unix UTC time for use by a module which schedules transmission of position reports to the user.

Requirements, system architecture, and complete design documentation make it easy to follow the source code, or to make changes and additions.

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.

ST was the first silicon vendor to introduce a Cortex-M7 chip.  Like the M4, the M7 has a floating point processor, and a specialized I2S peripheral called the SAI (Serial Audio Interface, I guess).

Floating point is a big help in computing envelopes for audio outputs.

The M7 also runs twice as fast as the M4.

The STM32F7-DISCO board includes an audio codec, the wm8994, and an audio output that works either for headphones or powered speakers.  In addition it has a 420 x 272 touchscreen, and a TFT color LCD.

So the hardware needed for the theremin is already in place.

All that was needed was the code, which this book provides.

Writing code for modern ARM processors is sometimes a challenging activity.  There are a great many modern peripherals on chip.  So many in fact that there are seldom enough processor pins to accommodate all the peripherals on the chip.  So only certain combinations of peripherals can be used at the same time.  Each peripheral must have its clock individually configured, and there are multiple layers to the chip libraries.  It is a good idea to have a completed project to use as a model.

Every detail of the development, from requirements through testing and validation is documented in the chapters of this book.  All of the code included in the final product is included in this book.  It is also available as source code, and in digital form as an extra you can download when you purchase the book. Just go to your leanpub library, click the XY Theremin icon there, and then click the extras entry in the menu that appears in the bottom half of the Library screen.

One of several free development environments is described, along with links to the silicon vendor's design and debugging tools.

There are several possibilities for expansion of the program.  One might add a capability of recording and playing back tracks played on the device using a micro-sdcard slot on the board.  It should be possible to add a 24dB per octave, variable cutoff, resonant filter to replace the simple smoothing filter supplied.

I wasn't interested in recording, and wasn't able to get the fancy filter working.