Appendix A: Deciphering Datasheets and Schematics

At the heart of all Arduinos is a microcontroller (or MCU for short). This appendix does not summarize the features of every microcontroller in every Arduino, but it does provide a brief guide to reading and understanding datasheets. Specifically, it examines elements of the Microchip (previously Atmel) ATmega328P (the MCU used in an Arduino Uno). In addition to understanding component datasheets, learning how to read the key parts of a schematic is a critical skill. This appendix investigates the schematic for the Arduino Uno, so that you can get a better idea of how an Arduino actually works.