For [Davide Gironi] made a holiday tie tack this year. It’s not made to look like Santa Claus, Frosty, or a Christmas tree. He simply wishes you a Merry Christmas (‘Buon Natale’ in Italian) by flashing the message in Morse code.
Two LEDs have been added to a plain tie tack. It is tethered to the logic circuitry that provides power and drives the red and blue lights accordingly. As you can see in the video after the break, red signifies the end of a letter, and long or short blue flashes correspond to dashes or dots. This doesn’t require much horsepower so he’s gone with an 8-pin ATtiny13 microcontroller (you might be able to find one of these in a light bulb if you look hard enough). The rest of the equipment includes a few resistors, a push button, and a coin cell for power. [Davide] uses a byte-packing technique he learned from a different project to store each letter as an 8-bit packet which means there’s plenty of room to store your message in the chip’s memory.