ESP32 with MAX30100 HEART SENSOR

31-07-2025

❤️ Heart Rate & SpO₂ Sensor (MAX30100/MAX30102)

🔬 Pulse Sensor | SpO₂ Monitor | Wearable Health Tech

The MAX30100/MAX30102 is a digital pulse oximeter and heart-rate sensor developed by Maxim Integrated. It’s commonly used in fitness bands, medical devices, and IoT-based health monitoring systems. It combines two key measurements in one module: heart rate (BPM) and blood oxygen saturation (SpO₂ %).

🔧 Key Features

Feature	Description
Heart Rate Range	30 to 240 BPM
SpO₂ Range	70 to 100%
LED Wavelengths	Red (660nm), IR (940nm)
Interface	I²C
Supply Voltage	1.8V to 3.3V (VIN can tolerate 5V in some modules)
Built-in Algorithm	Pulse detection, SpO₂ calculation
Low Power	Ideal for wearable and battery-powered devices
Package Size	~5.6 x 3.3 x 1.6 mm

🧠 How It Works

1. Heart Rate Measurement

The infrared LED emits light into the finger or skin.
A photodetector measures the reflection, which varies with each heartbeat due to blood flow changes.
The waveform is analyzed to detect pulse and compute beats per minute (BPM).

2. SpO₂ Measurement

Uses red and infrared light to measure the ratio of oxygenated to deoxygenated hemoglobin.
The light absorption difference gives an estimate of oxygen saturation in the blood.

🔌 Connections (I²C Mode)

MAX30100 Pin	Arduino/ESP32 Pin
VIN	3.3V (or 5V with onboard regulator)
GND	GND
SDA	A4 (Arduino) / GPIO 21 (ESP32)
SCL	A5 (Arduino) / GPIO 22 (ESP32)
INT (optional)	Not connected or GPIO (for interrupts)

📦 Typical Applications

🧠 Health and fitness trackers
📟 Wearable health monitors
🏥 Remote patient monitoring systems
📱 Mobile health applications
🧪 Biomedical IoT projects
🚨 Emergency health alert systems

📌 Note: Place your finger gently and keep it still for accurate readings.

📌 Notes

Avoid bright ambient light or motion for stable readings.
Use a rubber band or clip to hold your finger steady.
Some modules need a small delay after pox.begin() to stabilize readings.
Suitable for wearable applications and long-term monitoring.

HOW TO OPERATE

#include <Wire.h>
#include "MAX30100_PulseOximeter.h"

#define REPORTING_PERIOD_MS 1000

PulseOximeter pox;
uint32_t tsLastReport = 0;

void onBeatDetected() {
Serial.println("❤️ Beat Detected!");
}

void setup() {
Serial.begin(115200);
Serial.println("Initializing MAX30100 sensor...");

if (!pox.begin()) {
Serial.println("MAX30100 not detected. Please check connections.");
while (1);
}

pox.setOnBeatDetectedCallback(onBeatDetected);
}

void loop() {
pox.update();

if (millis() - tsLastReport > REPORTING_PERIOD_MS) {
Serial.print("Heart Rate: ");
Serial.print(pox.getHeartRate());
Serial.print(" BPM | SpO2: ");
Serial.print(pox.getSpO2());
Serial.println(" %");

tsLastReport = millis();
}
}