Altitude geocache is an ATMega328 based geocache of a formfactor of 1602 LCD. The goal is to move the geocache higher preset amount from the point it was powered on in a preset time limit. It could be a hill near by, a tall structure or anything else. Careful selection of the place is crucial to the user experience. You can place it the way it is obvious where to take it or make the cacher wonder 'now what?' You can place it and set the goal the way the cacher must find a lower place first, start there to find a higher place. After completing the goal, a new set of coordinates (to the final cache) is displayed on the display.

The geocache is equipped with air pressure sensor to calculate actual altitude. The air pressure sensor is very precise and can register changes in altitude down to 10cm. It's powered from two AAA batteries hidden under the LCD. Ultimate lithium batteries are recommended for extreme cold weather. It survived -30°C Maine winter. Batteries can last few years when the cache is in the sleep mode. The geocache has one button to wake it up from sleep and to advance to the next screen. Geocache can be reprogrammed using ISP header, your programmer must be 3.3V. Using 5V programmer may destroy the cache. Also the microcontroller is run by internal oscilator. Do not set the fuse to use external oscilator or it will brick the cache. Reference source code is on github. To program it from Arduino IDE, select Arduino Pro Mini 8Mhz 3.3V as a target board.

By pressing the button you can advance between screens, imperial and metric is available and also some debug screens. If the battery is too low the backlight is turned low or off to help save power so one can finish the game.

The cache normally ships unprogrammed, but can be programmed with the reference firmware upon request. Goal altitude difference, time limit, final coordinates and metric/imperial display can be customized.

3.3V ICSP programmer is required to program the cache. I sell few options:

• ICSP level shifter from 5V to 3.3V
• USBTinyISP 3.3V programmer
• 3.3V AVR programmer shield for Arduino Nano

We all like to find unique geocaches, therefore I will be limiting sale to one/two caches per country/state/similar area to prevent over saturation. First come first serve.

As seen on EEVblog

Check this video

Not into geocaching?

Then create a weather station! Use the barometric sensor to predict a weather.