The backwoods logger mini from Big mess o’wires is a thermometer and altimeter for logging your cross country hikes. It is an updated version of the backwoods logger classic. A production test run of pre-assembled units is available for sale. All the PCB files, as well as the source code are available.
It measures temperature and air pressure, elevation is derived from the change of pressure. The sensor information, as well as graphs over time are displayed on a OLED display. It also has a screenshot function to save current data on the display for latter review. Using one AAA battery it can go up to 5 months before a recharge or replacement is needed.