Overview

धड़क is a Pulse Oximeter which plugs onto a finger and measures SpO₂% and Heart rate of person.

• Design doesn’t use any specific oximeter sensor. A photodiode is used in the front end along with clean and amplify stages to obtain a suitable signal.

• ATmega4808 microcontroller is used in design along with QSB34CGR photodiode.

Specifications

• Runs on 2 AAA Batteries (MN2400).
• Takes 15 secs max to find parameters (can find earlier, depends on subject’s skin as leds adjust intensity to obtain a good response).
• Max average current draw: 25mA( This is the maximum draw when leds at full brightness). As per battery’s datasheet and minimum operating voltage of 2.7V, this would give a continuous operation time of 13hrs.
• 3 sec display update rate.
• Battery percentage indicator.
• Snap-fit enclosure with spring mechanism which ensures good firm contact of finger with photodiode.
• Soft latch power On/Off main button.
• 17KB Flash memory usage.

Documentation

Complete understanding document detailing the overview, circuit design, block diagrams, and algorithm is available below for 2 languages, Hindi & English:

github.com/yskab