Pumpkin Eyes Follow You!

While embedded firmware engineer Braden Sunwold didn’t really celebrate Halloween as a child, he’s since learned to enjoy it quite a bit. Perhaps not coincidentally, his brother-in-law is a bit of a Halloween nut, and after recently buying a house, he wanted to turn it into a scary attraction for locals. Naturally, Sunwold's maker-sense was triggered, and he got to work building an eye-following Halloween prop named Gourdan the gourd.

Gourdan features a pair of Adafruit 1.54 TFT displays loaded with their well known eyeball firmware. Instead of random blinks and glances, the hack-o'-lantern is equipped with a small camera, and a Raspberry Pi 3 running Open CV to track people as they move about the frame via a “stable camera” algorithm. While not the most advanced tracking method available, Sunwold wasn't able to obtain a Pi 4, so he decided to stick with this tried-and-true method.

One complication is that Adafruit’s TFT eyeball program only runs in headless mode. So while the project was modified to accept X/Y coordinates from the OpenCV results, actually tuning it directly based on camera input was not possible. The solution was to use two SD cards for the Raspberry Pi, one to tune the vision routine, and the other that runs the eyeball program with tuned settings.

TFT eyeballs, Pi, and camera, along with Sunwold's proto-power-hat that connects everything together, were installed into the faux gourd with the help of copious amounts of hot glue. A power button was added on the back for easy startup/shutdown, and an LED strip was recycled from the original pumpkin to light up the mouth. It should be a spooky attraction for visitors this year, and something that Sunwold may even improve on in the future!