Atmel's AVR microcontrollers are at the heart of the Arduino and are bountiful in the hobbyist and hardware hacker worlds. In this book you'll peel away the layers of abstraction provided by the Arduino environment and learn how to program AVR microcontrollers directly. Each chapter of this book is centered around projects that incorporate that particular microcontroller topic. Each project includes schematics, code, and illustrations of a working project. * Program a range of AVR chips * Extend and re-use other people's code and circuits * Interface with USB, I2C, and SPI peripheral devices * Learn to access the full range of power and speed of the microcontroller * Build projects including Cylon Eyes, a Square-Wave Organ, an AM Radio, a Passive Light-Sensor Alarm, Temperature Logger, and more * Learn what's really going on under the hood