Last week, we only used Arduino board as a power source, but the real power of the board is its ability to control input and output. We can write codes and upload to the board, plug in a sensor, and then a processor calculates our codes and output signals through digital and analog input/output (I/O). Sensors are like sense organs, reading signals in the physical world, and a processor is like the brain of Microcontroller, usually does only one task, like listening to sensors. The difference between digital and analog I/O is that digital signals have two states, ON (binary 1) or OFF (binary 0), while analog signals are variable.
In this week, I made a sound meter with LEDs to detect the level of sound, and the amount of LEDs would be illuminated accordingly. The louder the sound, the more LEDs emit.