A pulse oximeter monitors the oxygen saturation (SpO2) of a human’s blood based on the red light (600- 750 nm wavelength) and infrared light (850-1000 nm wavelength) absorption characteristics of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hb). The pulse oximeter flashes the red and infrared lights alternately through a finger to a photodiode. HbO2 absorbs more infrared light and allows more red light to pass through. On the other hand, Hb absorbs more red light and allows more infrared light to pass through. This application note demonstrates the implementation of a high-accuracy pulse oximeter using Microchip’s analog devices and dsPIC® Digital Signal Controllers (DSCs).