So I am taking on a project which involves to develop a heart rate monitor using the raspberry pi. I aim to take the signal using an IR sensor and a photo-diode sensor (like a finger sensor), and have this process using the raspberry pi. I know the Pi doesn't have an ADC. I am thinking to build a signal conditioning unit for the pi as well to treat the oncoming signal, however I am unsure of where to start this. Can anyone help me or give me some advice?
