Smart Environmental & Water Tank Monitoring System.

A wireless IoT system for monitoring environmental conditions (temperature, humidity, CO2) and water tank levels using ESP32 microcontrollers with ESP-NOW communication.

Features

• Sensor Node (Transmitter)

  • DHT11 temperature/humidity sensor
  • HC-SR04 ultrasonic distance sensor (water level)
  • MQ-135 air quality sensor (CO2 levels)
  • RGB LED status indicator
  • Buzzer alerts for warnings
  • Button calibration system

• Display Unit (Receiver)

  • ILI9341 TFT display interface
  • Real-time data visualization
  • Warning system for critical conditions
  • Auto-calibration prompts
  • Connection status monitoring

Hardware Requirements

Sensor Node

• ESP32 microcontroller
• DHT11 sensor
• HC-SR04 ultrasonic sensor
• MQ-135 gas sensor
• Passive buzzer
• Tactile button
• Common cathode RGB LED
• Breadboard & jumper wires

Display Unit

• ESP32 microcontroller
• ILI9341 2.8" TFT display
• Breadboard & jumper wires

Installation

1. Arduino IDE Setup

   • Install ESP32 board support
   • Required libraries:
     • DHT sensor library
     • ESP32 ESP-NOW
     • Adafruit SSD1306
     • Adafruit GFX Library
     • Adafruit ILI9341

2. Hardware Connections

   Sensor Node

   DHT11 -> GPIO17

   HC-SR04: Trig -> GPIO15 Echo -> GPIO18

   Buzzer -> GPIO19

   Button -> GPIO13 (pull-up)

   RGB LED: Red -> GPIO14 Green -> GPIO12 Blue -> GPIO27

   MQ-135 -> GPIO35

Display Unit

TFT_CS -> GPIO5

TFT_RST -> GPIO4

TFT_DC -> GPIO16

TFT_MOSI -> GPIO23

TFT_CLK -> GPIO18

Configuration

ESP-NOW Setup Update MAC addresses in both sketches:

// Transmitter code (replace with receiver MAC) uint8_t receiverMacAddress[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};

// Receiver code (replace with transmitter MAC) uint8_t expectedMac[] = {0x80,0x7D,0x3A,0xF8,0x1A,0x24};

Calibration

Initial calibration on first boot:

Hold button for 3 seconds

System measures empty tank distance

RGB LED confirms calibration

Usage

Sensor Node Automatically sends data every 500ms

Button press for recalibration

Visual alerts:

White: Normal operation

Blinking blue: Calibration needed

Blinking red: Warning condition

Display Unit

Shows real-time sensor data

Warning displays for:

Tank overflow/empty

Critical CO2 levels

Connection status monitoring

Customization

Adjust thresholds in waterTankStatus()

Modify update intervals:

const unsigned long updateInterval = 500; // Transmitter

const unsigned long displayTimeout = 5000; // Receiver

Enhance MQ-135 calibration (current implementation uses simple linear conversion)

Troubleshooting

Ensure MAC addresses match between devices

Check sensor wiring connections

Monitor serial output (115200 baud)

Reset both devices if connection drops

Note: This system requires line-of-sight between ESP32 devices for reliable ESP-NOW communication (range up to 200m in open space).

---

License

This project is licensed under the MIT License - see the LICENSE file for details.

---