Hello, I am helping a friend build a "photoplethysmograph" ( a device which will tell the heart rate of someone by attaching a pair of LED and a photodiode ).
I am trying to work out a software algorithm for it but my friend has a shortage of time, so I thought about posting it here also, so that if any body has made something like this before or can guide me the process will take much less time.
This is what I am planning to do.
Connect a photodiode and IR LED in proximity but insulated from each others so that when I put my fingertip on the LED and detector pair, the detector will recieve variable amount of light depending on the heartbeat pulse.(I think I am not being very clear, Take a look here: http://pulsesensor.com/
Now, what I think I will do is, get that signal, filter and amplify it to get a series of pulses that will correspond to the heartbeat. But how do I count those pulses? This is a part where I am a little confused. I am trying to find a way but if anybody can guide me it will be great.