Halloween is only a few days away. We’re getting into the spirit by building a remote control color changing pumpkin. Channel buttons 0-8 on the remote toggle the colors of the rainbow. Button 9 activates an ‘angry pumpkin’ mode that flashes a scary red strobe for a few seconds.
It uses a minimal PIC 18F2550 circuit that decodes the remote control signals and drives a ShiftBrite color changing LED module. The F2550 is a USB PIC with a USB bootloader, so it’s technically a USB upgradable pumpkin too.
Full sized schematic image [PNG]. A PIC 18F2550 microcontroller decodes RC5 infrared remote control signals, and sends instructions to a ShiftBrite color-changing LED module. We used a PIC development board with SMD parts, but you could also build this on a breadboard or perf-board with through-hole parts.
The IR receiver converts infrared light from the remote control into a signal that the PIC microcontroller can decode. The receiver is connected to PORTB pin 2 (RB2) of the PIC. RB2 has an external interrupt with edge select that we used to trigger the IR decoder. RB2 also has a Schmitt buffer that cleans the incoming signal and helps prevents false triggers. All PORTB pins on the 18F2550 have internal pull-up resistors if your receiver is an old type that doesn’t have it’s own pull-up.
The color changing LED is a ShiftBrite module from Macetech.com. It’s driven by three PIC pins and powered by a 5volt supply.
The PIC firmware is a simple timer and interrupt-based RC5 remote control decoder. It bitbangs ShiftBrite color instructions based on the remote command codes received.
The firmware ignores the RC5 brand code and looks only at the command. It should understand any RC5 remote control. RC5 is a really common protocol, usually available as a Philips TV on universal remotes.
0. Off 1.Red 2.Orange 3.Yellow 4.Green 5.Blue 6.Indigo 7.Violet 8.White (all colors) 9.Angry pumpkin (~10 seconds)
The channel buttons 0-8 control the color. #9 plays a 10 second ‘angry pumpkin’ red strobe effect and returns to a solid color. There’s lots of room for more effects, fades, and other options.
We tried to make the top of the pumpkin shake in angry mode using offset-weight rumble motors from a game control pad. It wasn’t violent enough to look good in a video, though it does make quite a racket. Next year we’ll try it again with a solenoid.