Let's first see what components are needed for this project. As an example in this chapter, I will use a project I have previously worked on, which is a low-power Arduino board. This board has just the bare minimum of components to be usable. This way, no power is wasted on components that are not necessary when the system is operating, such as LEDs, a USB interface, and so on. This board can then be used in very low-power applications such as motion sensors based on XBee.

The most important component in this project will be the microcontroller itself. The microcontroller is at the heart of all Arduino boards. It is the component that we program every time we write a new sketch.

I based my design on the Arduino Uno board design, so I used the same Atmel ATmega328 controller as the Arduino Uno board. For this project, you will need one of these microcontrollers, which are sold separately. Please make sure that you are buying one with the Arduino bootloader...