I found a little heart rate sensor @ ICstation. It is a clone of the open hardware pulse sensor. The sensor is well documented, and it comes with Arduino and Processing example code.
To try it out I connected the sensor to an ATmega328 running at 3.3V and loaded the example Arduino code. I could now see my heart beat on the Arduino serial monitor 🙂
I then connected a 2.2″ TFT display to the Arduino and tried to figure out how to display the sensor output on it. Sounds simple but unfortunately it isn’t. Updating the full screen (320×240 pixels) is really slow. So I needed some smarter code to update only the pixels that needed to change. I happened to stumble on Matthew McMillans blog, he wrote some smart code to use a similar display as a speedometer. So I borrowed some of his code and mixed it with the example code of the pulse sensor. You can see the result in the above video.
Download the code here.