This is a simple project using the Adafruit Heart Rate Educational Starter Pack.
- heart_rate_monitor.py monitors the GPIO pin connected to the heart rate monitor, and writes a timestamp to the database for each heartbeat.
- hrm.php queries the database, and outputs JSON giving a count of how many beats occurred each minute.
- index.html displays a graph of the heart beat frequency.
- script.js is what actually requests the JSON and draws the graph.
- style.css makes everything look nice.
The last 3 files are from http://bl.ocks.org/aogriffiths/7933339. The Javascript and HTML files were adapted somewhat for this project, but the CSS file is unchanged.
When loading index.html in a browser, a graph like this will be shown:
To make the circuit:
- Connect the + and - of a 2-AA battery holder to a breadboard
- Connect the + and - of the heart rate receiver to the same rails
- Connect the third pin of the receiver to a pin of the Raspberry Pi. I used pin 23.
- Connect the ground rail to the ground of the Raspberry Pi.
- I also connected an LED, by also connecting the data pin to the + of the LED, and connecting the - pin of the LED to a resistor which is plugged into the ground rail.
Circuit photo:
Video:
