ESP32 IoT Health Monitor Arduino IoT Cloud Open Source Live Dashboard

// IoT Health Monitoring System

VitalSync

Real-time SPO₂ · Heart Rate · Temperature → Cloud

A wall-powered IoT health station built on ESP32 that measures blood oxygen saturation, heart rate, and body temperature — displayed locally on an OLED and synchronized live to Arduino IoT Cloud.

View on GitHub Arduino IoT Cloud ↗

Language C++ / Arduino

Platform ESP32

License MIT

Cloud Arduino IoT

Author Prince Jha

♥

Heart Rate

BPM

◎

Blood Oxygen

SpO₂ %

⊕

Temperature

98.4

°F

// 01 — Features

What VitalSync Does

Real-Time Heart Rate

Custom peak-detection algorithm using exponential moving average baseline. Accurate on low-amplitude PPG signals where standard libraries fail.

SpO₂ Measurement

Maxim's official ratio-of-ratios SpO₂ algorithm over 100-sample rolling buffer with real-time validation.

Body Temperature

DS18B20 non-blocking temperature read every 3s. Displays simultaneously in °F and °C with clinical status text.

OLED Display

Two auto-rotating pages every 4 seconds. Page 1: BPM + SpO₂ with live waveform. Page 2: Temperature in both units.

Arduino IoT Cloud

4 variables pushed via MQTT/TLS every 5 seconds. Throttled cloud polling (100ms) prevents sensor loop interference.

Wall-Powered Hardware

12V DC → LM2596 Buck → 5V → AMS1117 → 3.3V. Clean regulated power for all components on a 6×4 perfboard.

Non-Blocking Architecture

Zero delay() calls. All timing via millis() timers. MAX30102 FIFO serviced every loop iteration without stalls.

Mobile App Ready

Live sensor data accessible from anywhere via the Arduino IoT Cloud mobile app — no server setup required.

// 02 — Hardware

Components

Component 01

ESP32 Dev Module

Main Microcontroller

Dual-core 240MHz Xtensa LX6. Built-in WiFi 802.11 b/g/n + Bluetooth. 12-bit ADC, hardware I2C/SPI. 3.3V logic.

Component 02

MAX30102 (Black PCB)

Pulse Oximeter + Heart Rate

Integrated red (660nm) + IR (880nm) LED with photodetector. 18-bit ADC. I2C address 0x57. PPG-based SpO₂ and BPM.

Component 03

DS18B20 (Black Wire)

Digital Temperature Sensor

Silicon bandgap thermometer. ±0.5°C accuracy. 11-bit resolution (0.125°C). 1-Wire protocol. −55°C to +125°C range.

Component 04

SSD1306 OLED 0.96"

Local Display

128×64 pixel OLED. No backlight needed — each pixel self-illuminates. I2C address 0x3C. High contrast, low power.

Component 05

LM2596 Buck Converter

12V → 5V Step-Down

Switching DC-DC converter. 75–90% efficiency. Handles up to 3A. Eliminates heat dissipation of a direct linear drop.

Component 06

AMS1117 3.3V LDO

5V → 3.3V Regulator

Low dropout linear regulator. Provides clean 3.3V for ESP32, OLED, MAX30102, and DS18B20 from the buck's 5V rail.

Component 07

4.7kΩ Resistor (¼W)

1-Wire Pull-up

Mandatory pull-up for DS18B20 1-Wire data line. Provides high logic level on open-drain bus. Between DATA and 3.3V.

Component 08

6×4 Perfboard

Custom PCB Assembly

Single-sided brown perfboard. All components soldered point-to-point. Compact and permanent assembly without a PCB fab.

// 03 — Wiring

Pin Connections

Component	Signal	ESP32 Pin	Note
MAX30102	SDA	GPIO 21	Shared I2C bus
MAX30102	SCL	GPIO 22	Shared I2C bus
MAX30102	VIN	3.3V	From AMS1117
OLED SSD1306	SDA	GPIO 21	Shared I2C bus (addr 0x3C)
OLED SSD1306	SCL	GPIO 22	Shared I2C bus
OLED SSD1306	VCC	3.3V	From AMS1117
DS18B20	DATA	GPIO 4	4.7kΩ pull-up to 3.3V
DS18B20	VCC	3.3V	From AMS1117
All GND	GND	GND	Common ground rail

// 04 — Communication Protocols

How Components Talk

I²C

Inter-Integrated Circuit

Used by MAX30102 (0x57) and OLED (0x3C) on the same 2-wire bus. SDA = GPIO 21, SCL = GPIO 22. Running at 400kHz Fast Mode. Master (ESP32) initiates all transfers. Open-drain with pull-ups.

1-Wire

Dallas 1-Wire

Used by DS18B20 on GPIO 4 with 4.7kΩ pull-up. Single bidirectional data line. Each DS18B20 has a unique 64-bit ROM address. Non-blocking mode: requestTemperatures() then read 3s later.

MQTT / TLS

Message Queue Telemetry Transport

Publish-subscribe IoT protocol over TCP/IP port 8884. Broker: iot.arduino.cc. TLS encrypted. Persistent connection. 4 variables published ON_CHANGE, polled every 100ms to avoid blocking.

WiFi 802.11

Wireless LAN

ESP32 connects to 2.4GHz hotspot. ConnectionHandler manages automatic reconnection. NTP (time.google.com) synchronizes clock required for Arduino IoT Cloud TLS authentication.

// 05 — Architecture

System Data Flow

MAX30102 ──I²C──▶ ESP32 ──▶ Peak Detector ──▶ BPM

MAX30102 ──I²C──▶ ESP32 ──▶ SpO₂ Algorithm ──▶ SpO₂%

DS18B20 ──1W──▶ ESP32 ──▶ F = C×9/5+32 ──▶ °F / °C

BPM + SpO₂ + Temp ──▶ OLED Display & WiFi → MQTT → Arduino IoT Cloud

Non-Blocking Loop Architecture

        // Loop runs at full speed — no delay() anywhere
        void loop() {
        // Cloud poll — throttled to 100ms
        if (now - lastCloudPoll >= 100)
        ArduinoCloud.update();

        // DS18B20 — every 3000ms, non-blocking
        if (now - lastTempRead >= 3000)
        readTemperature();

        // MAX30102 — service FIFO every iteration
        while (!particleSensor.available()) particleSensor.check();
        irVal = particleSensor.getIR();
        redVal = particleSensor.getRed();
        particleSensor.nextSample();

        // Custom peak detector → BPM
        detectBeat(irVal);

        // SpO2 buffer → recalculate at 100 samples
        accumulateSpO2(irVal, redVal);

        // OLED refresh — every 150ms
        if (now - lastDisplay >= 150) updateDisplay();

        // Cloud push — every 5000ms
        if (now - lastCloudUpd >= 5000) pushToCloud();
        }
      

// 06 — Cloud

Arduino IoT Cloud Variables

Define these four variables in your Thing on create.arduino.cc/iot before uploading.

heartRate

int

READ · ON_CHANGE

spo2Level

int

READ · ON_CHANGE

temperatureF

float

READ · ON_CHANGE

temperatureC

float

READ · ON_CHANGE

        // thingProperties.h — fill in your credentials
        const char DEVICE_LOGIN_NAME[] = "YOUR_DEVICE_ID";
        const char SSID[] = "YOUR_WIFI_SSID";
        const char PASS[] = "YOUR_WIFI_PASSWORD";
        const char DEVICE_KEY[] = "YOUR_SECRET_KEY";
      

// 07 — Installation

Getting Started

Clone the Repository

git clone https://github.com/iprince10/VitalSync_HealthMonitoringSystem.git and open the .ino file in Arduino IDE.

Install ESP32 Board Package

In Arduino IDE → Board Manager → search esp32 by Espressif → Install.

Install Required Libraries

Via Library Manager install: SparkFun MAX3010x, DallasTemperature, OneWire, Adafruit SSD1306, Adafruit GFX, ArduinoIoTCloud, Arduino_ConnectionHandler.

Create Arduino IoT Cloud Thing

Go to create.arduino.cc/iot, create a Thing named HealthMonitor, add the 4 cloud variables above, register an ESP32 device, and save the Device ID + Secret Key.

Configure Credentials

Edit thingProperties.h — fill in your Device ID, Secret Key, WiFi SSID, and WiFi password. Never commit this file publicly.

Upload and Monitor

Select board ESP32 Dev Module, select your COM port, upload. Open Serial Monitor at 115200 baud to observe connection logs and sensor values.

VitalSync

What VitalSync Does

Components

Pin Connections

How Components Talk

System Data Flow

Non-Blocking Loop Architecture

Arduino IoT Cloud Variables

Getting Started

Clone the Repository

Install ESP32 Board Package

Install Required Libraries

Create Arduino IoT Cloud Thing

Configure Credentials

Upload and Monitor

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