What is the Arduino?

At the heart of the Arduino is the microcontroller. A microcontroller is a standalone, single-chip integrated circuit that contains a CPU, read-only memory, random access memory and various I/O busses. Most Arduino boards use the Atmel 8-bit AVR microcontroller.

The Arduino UNO R3, which is the primary board used in this book, uses the ATmega328 chip. This chip is an 8-bit RISC-based microcontroller that features 32 KB of flash memory with read-write capabilities, 1 Kbyte EEPROM, 2 Kbytes SRAM, 23-general purpose I/O lines and 32 general-purpose registers. Do not be too concerned if you do not understand all those specifications because we will be interacting with the microcontroller using the interface that the Arduino board provides us. It is good to know these specifications as you begin to develop more complex applications because they do put limits on what we can do.

All the hardware and software that make up the Arduino platform are distributed as open source and licensed under the GNU Lesser General Public License (LGPL) or the GNU General Public License (GPL). This allows for the manufacture and distribution of Arduino boards by anyone and has led to numerous generic, lower cost, Arduino compatible boards.