I bought myself a cheap wearable Bluetooth LE heart rate monitor in order to play with it, and this is a simple Python script to monitor it and plot data.
Bluetooth LE
I was surprised that these things seem decently interoperable.
You can use hcitool to scan for devices:
hcitool lescan
You can then use gatttool to connect to device and poke at them interactively
from a command line.
Bluetooth LE from Python
There is a nice library called Bleak which is also packaged in Debian. It's modern Python with asyncio and works beautifully!
Heart rate monitors
Things I learnt:
- The UUID for the heart rate interface starts with
00002a37. - The UUID for checking battery status starts with
00002a19. - A longer list of UUIDs is here.
- The layout of heart rate data packets and some Python code to parse them
- What are RR values
How about a proper fitness tracker?
I found OpenTracks, also on F-Droid, which seems nice
Why script it from a desktop computer?
The question is: why not?
A fitness tracker on a phone is useful, but there are lots of silly things one can do from one's computer that one can't do from a phone. A heart rate monitor is, after all, one more input device, and there are never enough input devices!
There are so many extremely important use cases that seem entirely unexplored:
- Log your heart rate with your git commits!
- Add your heart rate as a header in your emails!
- Correlate heart rate information with your work activity tracker to find out what tasks stress you the most!
- Sync ping intervals with your own heartbeat, so you get faster replies when you're more anxious!
- Configure workrave to block your keyboard if you get too excited, to improve the quality of your mailing list contributions!
- You can monitor the monitor script of the heart rate monitor that monitors you! Forget buffalo, be your monitor monitor monitor monitor monitor monitor monitor monitor...