Sensor Logging with Beaglebone Black

Environmental Monitoring using Single-board Computer

Long-term sensor data logging requires large storage space (in embedded terms), which is often not easily accessible using 8-bit microcontrollers. The Beaglebone Black with internet access and a 16GB microSD card solves this problem nicely: recorded data can be stored on the card until read out via Ethernet/WiFi, and the excess processing power can be used for pre-processing like filtering, plotting and web page hosting.

A BMP180 barometric pressure sensor and an HTU21D humidity sensor are connected to a Beaglebone Black via I2C. Technologies used:

• OS: Debian for ARM

• Data processing: Python and matplotlib

• Storage: SQLite

• Task scheduling: crontab

• Webpage generation: a tiny bit of Jinja2 for HTML template

• Web hosting: Apache and CGI with Python

So many pieces of tech for such a simple task.

Ear Popping on Airplanes

Here's one recorded during a flight from Denver to LA (the date is incorrect - the BBB didn't have a real-time clock installed at the time):

So the air pressure in Los Angeles really is higher than that in Denver. My ears pop every time during take off and landing and I always wondered whether it is popping "out" or "in". Now I know it's more complicated than that. Interesting to know, hope I didn't break any law (shouldn't; smartphones these days have barometric pressure sensors built-in).

This led to a research project.