Heart Rate monitor help needed

[Keevashski]

hi guys
I am currently trying to build a heart rate monitor but don't know where to start with the coding, does anybody have a skeleton version for a heart rate monitor with macros and instructions so i can tailor it to my sensor.
Thanks very much
Keevash

[Benj]

Hello Keevash,

The should be fairly straight forward depending on which sensor you're using.

A light sensor and a LED should suffice for a sensor but you may want something that's more of an all in one package.

I would simply use an ADC input to monitor the voltage coming from the sensor. The ADC would be sampled at a reasonably high rate and we would look for the major peaks and maybe also the troughs. Once you have a base line you set a threshold level with a tolerance and then count how many times the signal goes over the threshold in a specific fixed time frame. Using some simple calculations this should then give you a usable BPM.

If the sensor provides a digital output then you can simply use this to drive an interrupt pin and just count the number of interrupts in a time frame, there is an example of this here.
http://www.matrixtsl.com/wikiv7/index.p ... Interrupts

Have a go and post your program so far and we can comment on what you can do to try and improve things.