Chapter 1, page 11 This code is basic but allows the reader to gain insight into key elements for several other projects in this book. It combines two pieces of code that are listed in the examples ...

The code inside the Arduino loop is essentially a state machine. In the IDLE state, it looks for a reading that is below the idle limit. When found, that causes a transition to the sampling state.

T he Arduino-sounding bit of the name comes from their full compatibility with the Arduino development environment. The brains of the board is the compatible, SAMD21 ARM M0+ chip.