Big Mess o' Wires

Build Your Own Backwoods Logger! See details below.

The Backwoods Logger is a programmable device for measuring and graphing altitude, temperature, and air pressure. It should appeal to any outdoorsy people interested in examining altitude, temperature, or pressure movements over timescales from an hour to two weeks. That includes hikers, climbers, skiers, trail runners, cyclists, kayakers, snowmobilers, horseback riders, and probably many others. You can get similar information from your GPS or altimeter watch, but few of those offer detailed graph views, and GPS’s don’t have the battery life needed for long trips in the wild. An app for a GPS-equipped smartphone might work, but toting your smartphone on your adventure isn’t ideal. The closest similar devices are probably the Garmin Foretrex 401, Garmin eTrex Summit (discontinued), or Suunto Core.

There are two versions of the logger: The Logger Classic and Logger Mini. The Classic uses all through-hole components, an 84 x 48 LCD screen, and a 3V CR2032 coin battery. The Mini uses all surface-mount components and is about half the size of the Classic. It uses a 128 x 64 OLED screen and a 1.5V AAA battery with a DC boost converter circuit to generate 3V. Both devices use an ATMega328P microcontroller and a Bosch BMP085 pressure/temperature sensor.

Both devices are designed to be as power-efficient as possible, with an average current consumption in the tens of microamps. Predicted battery life is about four months for the Logger Mini and six months for the Logger Classic.

Pressure, temperature, and altitude samples (computed from pressure) are taken once per minute. Short-term sample history is maintained in RAM, and longer term history in EEPROM to survive battery replacement or reset. Custom software displays graphs of historical sample data, and enables sample-by-sample examination of the graphs.

The Backwoods Logger was previously named Backcountry Logger.

Make Your Own

Building your own Backwoods Logger is easy. The Logger is an open source, open hardware project. Visit the Backwoods Logger project homepage to get all the firmware source code, schematics, board layouts, Gerbers, parts lists, and everything else you need. You can build a copy of the Logger Classic or Logger Mini, or design your own version by modifying the hardware and firmware to meet your needs. If you make some improvements you’d like to share, join the project and add them to the source repository.

The total parts cost for either version of the Backwoods Logger is about $40. The Logger Classic can be assembled in an hour or two, and is fairly easy to build. The Logger Mini is a bit more challenging to build, due to the use of surface-mount parts, but the result is a much more compact and professional-looking device.

You can make PCBs using the Gerber files included in the file distribution, or ask the Backwoods Logger discussion mailing list if anyone has any extra PCBs to share. You can also build the Backwoods Logger on a breadboard, following the Logger Classic schematics.

Buying a Logger

Don’t want to build your own? I made a small production run of Backwoods Logger Mini units, and I’m offering them for sale for $59. Send me email for more details or to purchase one.

Need a PCB? I am also selling bare Logger Mini PCBs for $3.