Electronic building block

When I want to build something, whether it is prototyping something with the Arduino, coding an application or building wooden steps to our back door, I usually try to break the project down into individual blocks. It really helps me focus on each individual part of the design rather than getting overwhelmed by the whole design. We can usually break an electronic project into four separate blocks. The following diagram illustrates how these blocks work together:

Let's look at each one of these blocks starting with the power supply.