SMART-INDUSTRIAL-SAFETY-EQUIPMENT-MONITORING-SYSTEM

This presents the design, implementation, and evaluation of a Smart Industrial Safety and Equipment Monitoring System built around the ESP32 microcontroller.

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Smart Industrial Safety & Equipment Monitoring System

ESP32 + WiFi WebSocket Dashboard — Complete Project Guide

Table of Contents

  1. Project Overview
  2. Features
  3. Hardware Required
  4. Circuit & Wiring Connections
  5. Relay (JQC3F) Wiring Detail
  6. Project Folder Structure
  7. Files to Edit Before Running
  8. Software Prerequisites
  9. Step-by-Step Setup & Execution
  10. Using the Dashboard
  11. Threshold Configuration
  12. Sensor Calibration Notes
  13. Troubleshooting
  14. Library Reference
  15. Project Images

1. Project Overview

This system uses an ESP32 Development Board as the central controller. It reads data from four types of industrial sensors (temperature/humidity, gas, flame, vibration), triggers physical actuators (relay-driven cooling fan, buzzer, LED) when thresholds are exceeded, and simultaneously serves a real-time web dashboard over your local WiFi network.

The dashboard runs entirely in your browser — no Python installation required. It connects to the ESP32 directly via WebSocket for near-zero-latency live data, renders scrolling charts for all sensors, displays alarm banners, and lets you change threshold values on-the-fly that are pushed back to the ESP32 immediately.

2. Features

  • Environmental Monitoring — Temperature (°C) and Relative Humidity (%) via DHT11
  • Air Quality / Gas Detection — Analog MQ-135 sensor, raw ADC value (0–4095), ideal for smoke, CO₂, ammonia, alcohol vapour detection
  • Flame Detection — Digital output from IR flame sensor module; immediate fire alarm
  • Machine Vibration Monitoring — SW-420 vibration sensor; detects shock or abnormal machine operation
  • Automated Physical Response — Fan via JQC3F relay (activates on high temp / gas / fire), buzzer and LED alarm on any threshold breach
  • WiFi WebSocket Server — ESP32 hosts its own HTTP + WebSocket server; data pushed every 500 ms to all connected dashboards
  • Dark-Mode Web Dashboard — Open dashboard/index.html in any browser; enter ESP32 IP to connect
  • Live Scrolling Charts — Separate time-series charts for temperature, humidity, gas level, and an event timeline showing when each alarm type was active
  • Configurable Thresholds — Change temp, humidity, gas thresholds from the dashboard; values sent to ESP32 via WebSocket and take effect immediately
  • Toggle Alerts — Fire and vibration alerts can be individually enabled/disabled from the dashboard
  • Alert Banner — Prominent flashing red banner with specific alarm description whenever any threshold is breached
  • Event Log Table — Every reading stored in a scrollable table; download as CSV with one click

3. Hardware Required

# Component Specification Quantity
1 ESP32 Development Board 38-pin or 30-pin, with USB-to-Serial 1
2 DHT11 Sensor Temperature + Humidity 1
3 MQ-135 Gas Sensor Module With analog A0 output pin 1
4 Flame Sensor Module IR-based, with D0 digital output 1
5 SW-420 Vibration Sensor Module With D0 digital output, adjustable sensitivity 1
6 JQC3F Relay Module 5V DC coil, single channel 1
7 5V DC Cooling Fan Any small PC/industrial fan, 5V 1
8 Active Buzzer 3.3V or 5V compatible 1
9 Red LED 5mm through-hole 1
10 Resistor 220Ω 1
11 NPN Transistor 2N2222 or BC547 (for relay driver) 1
12 Flyback Diode 1N4007 1
13 Breadboard Full-size or half-size 1
14 Jumper Wires Male-to-Male, Male-to-Female assortment ~30
15 USB Cable Micro-USB or USB-C (matching your ESP32) 1
16 5V Power Supply USB power bank or 5V 2A adapter 1

4. Circuit & Wiring Connections

⚠️ IMPORTANT: Always disconnect power before making or changing connections. The ESP32 runs at 3.3V logic. Never connect 5V signals directly to GPIO pins.

4.1 Power Rails

From To Notes
ESP32 3V3 pin Breadboard 3.3V rail (+) Powers all sensors
ESP32 GND pin Breadboard GND rail (−) Common ground
External 5V Supply + Relay COM terminal Powers the fan circuit
External 5V Supply − Breadboard GND rail (−) Common ground — must share with ESP32 GND

4.2 DHT11 Temperature & Humidity Sensor

DHT11 Pin Connect To Notes
VCC / + 3.3V rail
GND / − GND rail
DATA / OUT ESP32 GPIO 4

Note: Add a 10kΩ pull-up resistor between DATA and VCC if your DHT11 is a bare sensor (not a module). DHT11 modules usually include this resistor on the PCB.

4.3 MQ-135 Gas / Air Quality Sensor

MQ-135 Pin Connect To Notes
VCC / + 3.3V rail Module can also use 5V — see note below
GND / − GND rail
A0 (Analog) ESP32 GPIO 34 ADC1 channel — do NOT use GPIO 35, 36, 39 for output
D0 (Digital) Not connected We use only analog output for precision

Note: MQ-135 has a heating element. Running it at 3.3V reduces sensitivity. For best results, power VCC from your 5V supply and use a voltage divider (10kΩ + 10kΩ) to bring A0 output from 0–5V down to 0–3.3V before connecting to GPIO34. Alternatively: power at 3.3V and calibrate the threshold accordingly. Wait 60 seconds after power-on for the sensor to preheat and stabilise.

4.4 Flame Sensor Module

Flame Sensor Pin Connect To Notes
VCC / + 3.3V rail
GND / − GND rail
D0 (Digital) ESP32 GPIO 27 LOW = flame detected

Orientation: Point the flame sensor's IR receiver toward the area you want to monitor. Keep it away from bright incandescent light sources which may cause false triggers.

4.5 SW-420 Vibration Sensor

SW-420 Pin Connect To Notes
VCC / + 3.3V rail
GND / − GND rail
D0 (Digital) ESP32 GPIO 26 HIGH = vibration detected

Sensitivity: The SW-420 has a small blue potentiometer. Turn it clockwise to increase sensitivity (detects smaller vibrations) or counter-clockwise to decrease (only detects strong shocks). Mount it firmly to the machine or surface you want to monitor.

4.6 Warning LED

LED Connection Connect To Notes
Anode (+, longer leg) ESP32 GPIO 2
Cathode (−, shorter leg) → 220Ω resistor → GND rail Always use current-limiting resistor

4.7 Active Buzzer

Buzzer Pin Connect To Notes
Positive (+) ESP32 GPIO 15
Negative (−) GND rail

If your buzzer requires 5V for adequate volume, use the same NPN transistor driver circuit described in section 5 below.

4.8 Relay Module (JQC3F 0-5V DC) — via Transistor Driver

Because the JQC3F relay coil requires 5V to operate reliably and the ESP32 GPIO pins output only 3.3V at ~12mA maximum, you must use a transistor driver circuit.

See Section 5 for the full transistor driver wiring diagram.

5. Relay (JQC3F) Wiring Detail

The JQC3F relay module has a 5V DC coil. Driving it directly from GPIO16 (3.3V, ~12mA) may cause unreliable switching. Use this transistor driver:

ESP32 GPIO16 ──────────── 1kΩ resistor ──────┐
                                              │
                                           Base (B) of NPN transistor (e.g. 2N2222)
                                              │
                                   Collector (C) ──────── Relay Coil Pin 1 (IN)
                                              │
5V Supply (+) ─────────────────────────────── Relay Coil Pin 2 (VCC on relay module)
                                              │
                               1N4007 diode ──┘ (Cathode to 5V, Anode to Collector)
                               [Flyback protection — prevents voltage spike]
                                              │
                                   Emitter (E) ──────── GND rail

Relay Load Wiring (for the Cooling Fan):

5V Supply (+) ────── Relay COM (Common) terminal
                     Relay NO  (Normally Open) ────── Fan (+) red wire
Fan (−) black wire ──────────────────────────────── GND rail / 5V Supply (−)

When GPIO16 goes HIGH → transistor conducts → relay coil energises → NO contact closes → Fan runs. When GPIO16 goes LOW → transistor cuts off → relay coil de-energises → NO contact opens → Fan stops.

Safety: The --relay ACTIVE_LOW firmware logic accounts for relay modules that have an inverter transistor built in. Check your relay module's IN pin behavior. If the fan turns on when it should be off, change LOW to HIGH (and vice versa) in the updateAlarms() function in main.cpp.

Complete Pin Summary Table

GPIO Component Direction Signal Logic
GPIO 2 LED Anode (+) OUTPUT HIGH = ON
GPIO 4 DHT11 DATA INPUT/OUTPUT 1-wire protocol
GPIO 15 Buzzer (+) OUTPUT HIGH = ON
GPIO 16 Relay transistor base (via 1kΩ) OUTPUT HIGH = Fan ON
GPIO 26 SW-420 D0 INPUT HIGH = vibration
GPIO 27 Flame Sensor D0 INPUT LOW = fire detected
GPIO 34 MQ-135 A0 INPUT (ADC) 0–3.3V → 0–4095

6. Project Folder Structure

After setting up, your project directory should look like this:

industrial_safety/
├── esp32_code/                     ← PlatformIO project root
│   ├── platformio.ini              ← Build config, libraries, board settings
│   └── src/
│       └── main.cpp                ← All ESP32 firmware code
│
├── dashboard/
│   └── index.html                  ← Open this in your browser (no server needed)
│
└── README.md                       ← This file

Files that will be auto-created at runtime:

  • sensor_log_YYYY-MM-DDTHH-MM-SS.csv — Downloaded from dashboard when you click "Download CSV"

7. Files to Edit Before Running

7.1 esp32_code/src/main.cpp — WiFi Credentials

Open the file and find lines 17–18 near the top:

const char* WIFI_SSID     = "YOUR_WIFI_SSID";      // <-- CHANGE THIS
const char* WIFI_PASSWORD = "YOUR_WIFI_PASSWORD";  // <-- CHANGE THIS

Replace YOUR_WIFI_SSID and YOUR_WIFI_PASSWORD with your actual WiFi network name and password. The ESP32 and the computer running the dashboard must be on the same WiFi network.

7.2 esp32_code/src/main.cpp — Optional: Relay Logic

If your JQC3F relay module is active-HIGH (fan turns on when IN pin is HIGH), the default code is correct. If your module is active-LOW (fan turns on when IN pin is LOW — which is common for optocoupler-isolated relay boards), find the updateAlarms() function and swap LOW / HIGH:

// Active-LOW relay (most common optocoupler relay modules):
digitalWrite(RELAY_PIN, fanRunning ? LOW : HIGH);

// Active-HIGH relay (less common, bare relay driver):
digitalWrite(RELAY_PIN, fanRunning ? HIGH : LOW);

7.3 dashboard/index.html — Pre-fill ESP32 IP (Optional)

If you want the dashboard to pre-fill the ESP32 IP automatically, find this line in the <script> section:

// In the <input id="ip-input"> tag, change value="" to your ESP32 IP:

Or simply type the IP in the dashboard after loading it.

8. Software Prerequisites

8.1 For uploading ESP32 firmware

  • Visual Studio Code — https://code.visualstudio.com
  • PlatformIO IDE Extension — Install from VS Code Extensions (Ctrl+Shift+X, search "PlatformIO IDE")
  • USB Driver — Install CP210x or CH340 driver depending on your ESP32 board's USB chip

8.2 For the dashboard

  • Any modern web browser — Chrome, Firefox, Edge, or Safari
    • No Python, Node.js, or any server software needed
    • The dashboard is a single HTML file that connects directly to the ESP32

8.3 Libraries (auto-installed by PlatformIO)

PlatformIO reads platformio.ini and installs all libraries automatically on first build. The libraries used are:

Library Purpose Source
DHT sensor library by Adafruit Read DHT11 temperature/humidity PlatformIO registry
Adafruit Unified Sensor Dependency for DHT library PlatformIO registry
ArduinoJson by bblanchon Serialize/parse JSON over WebSocket PlatformIO registry
AsyncTCP by me-no-dev Async TCP layer for ESP32 PlatformIO registry
ESP Async WebServer by me-no-dev HTTP + WebSocket server PlatformIO registry

If PlatformIO cannot find AsyncTCP or ESP Async WebServer, install them manually:

  1. Click the PlatformIO icon in VS Code sidebar (alien icon)
  2. Go to Libraries
  3. Search for AsyncTCP and install me-no-dev/AsyncTCP
  4. Search for ESP Async WebServer and install me-no-dev/ESP Async WebServer

9. Step-by-Step Setup & Execution

Step 1 — Wire the Hardware

Follow the tables in Sections 4 and 5. Double-check:

  • All sensor VCC pins → 3.3V rail
  • All sensor GND pins → GND rail
  • GPIO assignments match the table in Section 5
  • Transistor driver circuit for relay is assembled correctly
  • Fan negative wire goes directly to the GND / 5V supply negative (not through the relay)

Step 2 — Install VS Code and PlatformIO

  1. Download and install VS Code from https://code.visualstudio.com
  2. Open VS Code → Extensions (Ctrl+Shift+X) → Search "PlatformIO IDE" → Install
  3. Restart VS Code after installation

Step 3 — Open the Project

  1. Click the PlatformIO icon (alien head) in the left sidebar
  2. Click "Open Project"
  3. Navigate to and select the industrial_safety/esp32_code folder
  4. VS Code will load the project and PlatformIO will index it (takes 30–60 seconds on first load)

Step 4 — Edit WiFi Credentials

  1. Open esp32_code/src/main.cpp in VS Code
  2. Find lines 17–18 and replace the SSID and password with your network credentials
  3. Save the file (Ctrl+S)

Step 5 — Connect ESP32

  1. Connect your ESP32 to your computer via USB cable
  2. The board should appear as a COM port (Windows: COM3, COM4, etc.) or device (Linux: /dev/ttyUSB0, Mac: /dev/cu.usbserial-*)
  3. If the port is not detected, install the USB-Serial driver:

Step 6 — Build and Upload Firmware

  1. In VS Code, press Ctrl+Shift+P (or Cmd+Shift+P on Mac)
  2. Type "PlatformIO: Upload" and press Enter
  3. PlatformIO will:
    • Install missing libraries automatically
    • Compile the firmware
    • Upload to the ESP32
  4. The upload is complete when you see ====== [SUCCESS] ====== in the terminal

If upload fails with "No device found", check:

  • USB cable is data-capable (not charge-only)
  • Correct COM port is selected (PlatformIO usually auto-detects)
  • Some ESP32 boards require pressing the BOOT button during upload

Step 7 — Find the ESP32's IP Address

  1. Open the PlatformIO Serial Monitor:
    • Click the plug icon (🔌) at the bottom VS Code toolbar, OR
    • Press Ctrl+Shift+P → "PlatformIO: Serial Monitor"
  2. Set baud rate to 115200
  3. Press the EN / RST button on the ESP32 to reset it
  4. You will see output like: === Industrial Safety Monitor - Booting === [WiFi] Connecting to MyNetwork.......... [WiFi] Connected! IP: 192.168.1.105 [WiFi] Open the dashboard at: http://192.168.1.105 [Server] HTTP + WebSocket server started.
  5. Note the IP address — you will need it for the dashboard.

Step 8 — Open the Dashboard

  1. In your file explorer, navigate to industrial_safety/dashboard/
  2. Open index.html by double-clicking it — it will open in your default browser
  3. In the top header bar, type the ESP32's IP address (e.g. 192.168.1.105) into the IP input field
  4. Click CONNECT
  5. The status indicator in the header will turn green and show CONNECTED
  6. Live data will start populating all cards and charts within 1 second

10. Using the Dashboard

Connection Status

The coloured dot in the top-right of the header shows connection state:

  • 🟢 Green pulsing = Connected, receiving data
  • 🔴 Red = Connection error
  • Grey = Disconnected

If the connection drops (e.g. WiFi interference), the dashboard will automatically retry every 3 seconds.

Sensor Cards

  • Temperature — Current °C reading; turns red with glow effect when above threshold
  • Humidity — Current %RH reading; alarm state shown
  • Gas / Air Quality — Raw ADC value 0–4095; higher = more gas/pollutants
  • Fire — Green circle = clear, Red = flame detected
  • Vibration — Green = stable, Red = vibration event detected
  • Actuator Status — Shows fan, buzzer, and LED state in real time

Charts

Four scrolling charts update in real time, retaining the last 60 data points:

  • Temperature history
  • Humidity history
  • Gas (ADC) history
  • Event Timeline — bar chart showing which alarms were active at each time step

Alert Banner

When any threshold is exceeded, a red flashing banner appears at the top of the dashboard listing the specific alarm(s). Click DISMISS to hide it until the next new alarm event.

Event Log

A table showing every reading. Alarm values are highlighted in red. Use the Download CSV button to save the full log to your computer for later analysis.

11. Threshold Configuration

The Threshold Configuration panel allows changing alarm trigger points from the dashboard. Changes are sent to the ESP32 in real time via WebSocket and take effect immediately — no firmware re-upload needed.

Parameter Default Description
Temperature Threshold 35°C Fan activates; alarm triggers above this
Humidity Threshold 80% Alarm triggers above this
Gas Threshold (ADC) 400 Alarm triggers above this raw ADC value
Fire Alert (toggle) Enabled Disable to suppress flame sensor alarms
Vibration Alert (toggle) Enabled Disable to suppress vibration alarms

Type a new value in the input box and click APPLY to send it. The ESP32 echoes back the updated value in its next broadcast, confirming receipt.

12. Sensor Calibration Notes

MQ-135 Preheating

The MQ-135 requires a 60-second warm-up period after power-on before readings are reliable. During this time, gas values will read artificially high and then settle. You can raise the gas threshold temporarily during startup.

DHT11 Accuracy

The DHT11 has an accuracy of ±2°C and ±5%RH. For higher precision, replace it with a DHT22 (±0.5°C, ±2%RH). If using DHT22, change line in main.cpp:

#define DHT_TYPE DHT22  // was DHT11

SW-420 Sensitivity

Adjust the blue potentiometer on the SW-420 module. Mount the sensor directly to the machine frame using adhesive or screws for best vibration coupling. Avoid mounting on rubber feet.

Flame Sensor Range

The flame sensor detects IR wavelengths from open flames (lighters, matches, candles, gas fires). It has a detection range of approximately 80cm at 0° angle, reducing to ~60cm at 60° angle. It is not designed to detect electrical fires without open flame.

13. Troubleshooting

Problem Possible Cause Solution
PlatformIO won't find COM port Missing USB driver Install CP210x or CH340 driver
Upload fails with timeout Boot mode issue Hold BOOT button on ESP32 during upload start
Dashboard shows "DISCONNECTED" Wrong IP address Check Serial Monitor for correct IP; verify same WiFi network
Temperature reads nan DHT11 wiring loose Check DATA pin connection to GPIO4; try adding 10kΩ pull-up
Gas reads 0 always GPIO34 not connected or A0 pin used incorrectly Ensure MQ-135 A0 (not D0) is connected to GPIO34
Fan won't turn on Relay logic inverted or transistor wiring Swap LOW/HIGH in updateAlarms(); check transistor pinout
Relay clicks but fan doesn't spin Fan wiring issue Verify COM → Fan+ → Fan− → GND; check fan voltage rating
Dashboard can't connect from different device CORS or network isolation Ensure all devices on same subnet; check router AP isolation setting
WebSocket drops frequently WiFi signal weak Move ESP32 closer to router; check for interference

14. Library Reference

All libraries are automatically installed by PlatformIO using the platformio.ini configuration.

DHT sensor library (Adafruit)

Reads temperature and humidity from DHT11/DHT22 sensors over the 1-wire protocol.

ArduinoJson (Benoit Blanchon)

Efficient JSON serialisation and deserialisation on embedded systems. Used to format sensor data as JSON for WebSocket transmission.

AsyncTCP (me-no-dev)

Asynchronous TCP library for ESP32. Required foundation for the web server.

ESP Async WebServer (me-no-dev)

Asynchronous HTTP and WebSocket server for ESP32. Handles multiple simultaneous dashboard clients without blocking sensor reads.

Dashboard Frontend Libraries (CDN, no installation)

  • Chart.js 4.4.1 — Loaded from Cloudflare CDN in the HTML file. No installation needed.
  • Google Fonts (Rajdhani, Share Tech Mono) — Loaded from fonts.googleapis.com. Requires internet connection for styling (dashboard still functions without it).

15. Project Images

Last updated: 2026. Designed for ESP32 Arduino framework via PlatformIO.

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