Arduino tone() Melody Player

Wire a small piezo disc to one pin, call tone(), and the Arduino plays "Twinkle Twinkle" — your first audio output from a microcontroller.

Difficulty: Breadboard. Estimated build time: about 25 minutes. Estimated parts cost: about US$2.00. 4-part bill of materials with live supplier pricing. An Arduino sketch that plays a recognisable tune on a passive piezo speaker by sequencing notes with the built-in tone() function.