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).
Update: this has turned into a research project.