The Backcountry Logger is a portable microcontroller-driven device that collects temperature, air pressure, and altitude data, and shows graphs on a built-in screen. It’s intended for hikers, climbers, skiers, and other outdoorsy folks who want to geek out with environmenal data about their activities.

I’ve written extensively already about the design and board layout of the Backcountry Logger, but never described its actual usage in any detail until now. I’d been waiting until I received the custom-designed board back from the PCB house, so I could move the project off the protoboard and onto a permanent frame. The board finally arrived a few days ago, and I had everything assembled after about an hour of soldering. It all worked flawlessly right away, so the transition from protoboard to PCB was very smooth.





The logger interface is organized as 16 different screens, and the user cycles through the list of screens using the PREV and NEXT buttons. Each screen displays status text or a graph of historical data. Most screens also have a menu that can be opened with the SELECT button, providing access to further customization and configuration options. Screens are grouped into altitude, temperature, and air pressure sections, with each section having historical graphs at time scales ranging between past 90 minutes to past 14 days.

The main screen shows a customizable summary of environmental data. By default it displays current altitude and temperature, rate of ascent, and time of day, but the contents are fully customizable from the menu. Each of the screen’s six lines can be configured to show one of eleven different statistics, such as weather forecast, current air pressure, and estimated time to a previously-set goal altitude.


One of my first tests was to take the logger up a nearby hill. Here you can see the 90-minute altitude graph from the test. The graph only goes back about 30 minutes, to the time when I inserted the battery and data collection began. The graph begins with a big spike down to about 300 feet when I calibrated the altitude. I then got in my car, and drove up a hill that’s about 470 feet according to the topo map. At this scale, each pixel on the X-axis reperesents one minute.


Here’s the 90-minute temperature graph from the same test. It was a hot day, and my car had been sitting out in the sun, so the interior of the car was sweltering. How sweltering? About 112F, according to the logger. Yikes!


The system screen contains lots of goodies like the firmware version number, current battery voltage, and LCD contrast setting. The system settings can all be edited via the screen’s menu.


This version of the Backcountry Logger is about 7 cm long, 4.5 cm wide, 2 cm tall, and weighs 1.3 ounces. It uses a 3V CR2032 battery, unregulated. The current consumption is about 1.5 mA when it’s on, and 20 uA when it’s asleep. Depending on how much it’s used, the battery life should be about 8-12 months.

The main board has only one IC: an ATmega328P. The rest of the space is consumed by the battery, piezo speaker, buttons, a few passive components, and headers. The LCD and BMP085 pressure/temperature sensor are mounted on breakout boards that plug into the headers.

I’m planning to make a version 3 of the Backcountry Logger that’s substantially smaller and lighter. (Don’t ask what happened to version 2.) This version will be just 5 x 3 cm, and will use a tiny OLED screen that’s higher-resolution than the LCD but physically much smaller. All the parts in version 3 will be surface mount, instead of this version’s through-hole parts. Because the OLED requires more current than the LCD, version 3 will use a single AAA battery with a voltage booster in place of the CR2032 battery. Check back in a few weeks, and I hope to have a version 3 demo to share.