Reverse Geocahes Proposal Box

Geocaching is an outdoor activity where you find a cache placed in a location, based GPS coordinates. While an interesting pursuit, another variation on this theme is a “reverse geocache” where you need to transport the box itself to a location in order for it to open and reveal its prize. In this case, Josh Robertson built his geocache project in order to propose to his partner, now-fiancé, which involved solving a couple extra riddles along the way.

This particular geocaching unit is built into a wine box, and uses an Adafruit Ultimate GPS module to sense its location, as well as two Arduino Uno boards for control. While a more capable device—perhaps an Arduino Mega—could have been used instead, Robertson decided to simply add another board after running out of I/O options. In his setup, one Arduino serves as the master. It communicates with the other board via I2C, receives signals from the GPS, and controls the LCD display. The slave in turn controls the device’s three lock servos, which move rods to keep things secure, and receives user input.

The finished device releases the first lock after solving a riddle with an onboard keypad, while the second is unlocked by placing its potentiometers in the correct position. Finally, the third pops off it's in the correct geographic position. The result, of course, is that Robertson is now engaged, and will presumably have to plan a new jaunt for their honeymoon!