Here we have a birds-eye view of the system as a whole. The function of the system is easy to track in the diagram below. It simply goes from left to right. First, input is received from the infra-red proximity sensors located under each of the 12 keys. This input is funneled through a multiplexer before reaching the Arduino Nano. Software determines the state of the key ie: key pressed verses not pressed, and then a command message in the form of MIDI serial data is sent to the VS1053B board module. The VS1053B board reads the MIDI messages and produces a corresponding analog audio signal. This signal is amplified through two on-board audio amplifiers before playing out of two 3W speakers. The user may pick from 24 available instruments, as well as control the volume with a volume knob in the form of a potentiometer. The whole system is powered from a wall outlet with 9V DC supply.