This instructable is about a small circuit which displays a smiley on a LED matrix, singing with the music input.
The circuit schematic, pcb and component placement files are included in the instructable.
The DS 1820 in the circuit is NOT necessary though I added it for future use. The pot on the right below is for testing purposes and can be omitted, it is not present in the PCB anyway.
The code is simple, all it does is to make an analog voltage measurement and get the corresponding image from ROM and display it on the LED dot matrix screen.