A Pulse Oximeter on an ATmega644 Microcontroller

By Cathy Chen and Shane Pryor

In this project, we seek to monitor a patient’s heart rate and blood-oxygen level using a
pulse oximeter. The pulse oximeter is designed using infrared and visible (red) light detection
from light that passes through a subject ’s finger from an emitter. The absorption will tell when
blood is moving through the finger and how much of this is oxygen-rich. The output of this
analog circuit will be fed into an Atmel ATmega644 microcontroller, which will compute the
pulse and oxygen level from these numbers. The microcontroller will output an NTSC video
signal to a black and white television so that the subject’s signals can be monitored.

Full report (pdf) (doc)