Raspberry Pi Marshmallow Smores

A roaring fire makes for a great excuse to toast a marshmallow on Christmas Day. I built a tiny fireplace complete with fire that is controlled by a Raspberry Pi computer.

At first a video of a fire plays continuously inside the box. But when a guest roasts a marshmallow, the scene changes to a ghostly head floating in the void. The disembodied head begins dim and faded. Then, in a short time, the figure grows into focus. The result: sudden hallelujah laugher-filled cheers erupt from onlookers peering into this strange diorama: “Hey. Whoa! Cool! That’s Diane!”, or “Woohoo!, It’s me!” The person who grew from the flames during this round becomes the next recipient of a gift from The Mad Wrapper!

Marshmallows that are attached to packages under the Christmas tree are made of polymer Sculpey clay. Baked into each clay marshmallow is a pair of RFID tags very similar to what one might find on the high-end merchandise in a store — you know: those those culprit stick-ons guilty of setting off alarms at the exit door when the cashier has forgotten to demagnetize your stuff. But there is a difference. When this RFID reader recognizes a tag, it does not set off an alarm. Instead, it prompts a computer to gently update the scene — phasing out the fire, and phasing in a floating head.

A Raspberry Pi computer is connected to a small monitor mounted at the top of the miniature custom fireplace. The display faces straight down. A piece of plexiglass set at a 45 degree angle reflects the image outward to the front for viewing. The invisible glass and dark background give the illusion of a head hovering in thin air. In the idle state, when a marshmallow has not been inserted for roasting, a video of a campfire plays continuously in the background. This fire comes from video footage of a family camping trip last July in Lake Durant, NY. Based on the message written onto the RFID tag inside the marshmallow, a photoshopped picture of a family member is phased in as the campfire image fades out.

The person whose head shows up in the campfire opens the gift and takes it away to enjoy.

(And there is a bonus gift this year: someone received a customized “Magic Eight Ball”. Great for the task of decision making. Ask a yes/no question and hold the eight-ball near the sensor in the fireplace. A blue triangle appears with the answer. There are quite a few possible answers that fad-history buffs will be familiar with. Such as: “It is decidedly so.” Or: “Reply hazy, try again.”)

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