Halloween is roughly two weeks away, meaning that if you’re going to hack out an interesting display to show off your spooky hacking prowess, you’d better get started! If you need some inspiration, “fadecomic” has come up with an excellent trio of pumpkins that “sing” along with classic Halloween songs like “Monster Mash” or whatever tune you program into it.
Hardware-wise, the build uses a Raspberry Pi for high level control and browser interface via Falcon Pi Player. Audio outputs are directly transferred to an external speaker system using a 3.5mm audio jack, while lighting and animation info is fed to an Arduino Uno over serial USB. The Uno then takes care of the low level functions, controlling a light show with a set of solid-state relays (SSRs), mouth movement using a relay for each pumpkin, and a pair of LED eyes driven directly via PWM.
As of now, the Uno’s six PWM outputs mean that the display is restricted to three pumpkins with motion and controllable lights, or six with no lights. Even so, the effect is quite good, allowing for a lead pumpkin singer, along with a pair of smaller backup singers to mouth the words to whatever is programmed in — a reportedly tedious process. Arduino code is available on GitHub, and thorough build instructions can be found here!