ESP32-based Smart Greenhouse Control With DHT Sensor (ThingSpeak)

by sarful in Circuits > Arduino

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ESP32-based Smart Greenhouse Control With DHT Sensor (ThingSpeak)

1 DHT22 - Digital Temperature and Humidity Sensors.png

This project uses an ESP32 board along with a DHT sensor (either DHT11 or DHT22) to monitor temperature and humidity inside a greenhouse. The data is uploaded to ThingSpeak, where it can be monitored and visualized in real time. Based on sensor readings, a relay module controls devices such as a fan and water pump to regulate temperature and humidity inside the greenhouse.

Supplies

Components Required:

  1. ESP32 Board – The microcontroller for IoT applications.
  2. DHT11 Sensor or DHT22 Sensor – Temperature and humidity sensor.
  3. Relay Module – Controls the fan and water pump.
  4. Water Pump – Automated irrigation based on humidity.
  5. Fan – Cooling system to control temperature.
  6. Breadboard – For connecting components.
  7. Jumper Wires – For wiring connections.
  8. Power Supply – To power the ESP32 and other devices.
  9. LCD Display (Optional) – To display temperature and humidity values locally.
  10. Push Button (Optional) – To manually control the fan and water pump.


Wiring Instructions:


  1. Connect the DHT Sensor:
  2. VCC of DHT to 3.3V on the ESP32.
  3. GND of DHT to GND on the ESP32.
  4. Data Pin of DHT to Pin D4 on the ESP32.
  5. Connect the Relay Module:
  6. Relay IN Pin to GPIO D5 (or any available pin on the ESP32).
  7. Relay VCC to 3.3V on the ESP32.
  8. Relay GND to GND on the ESP32.
  9. Common (COM) of the relay to the water pump or fan.
  10. Normally Open (NO) pin to the power supply of the device you want to control.
  11. Optional: LCD Display:
  12. Connect the LCD Display to the SDA and SCL pins of the ESP32 for I2C communication.
  13. Optional: Push Button:
  14. Connect the push button to GPIO D2 for manual control of the fan and water pump.

Setting Up ThingSpeak:

  1. Create a ThingSpeak Account:
  2. Go to ThingSpeak and sign up for a free account.
  3. Create a Channel:
  4. After logging in, create a new channel by going to Channels → Create New Channel.
  5. Add four fields: Temperature (Field 1), Humidity (Field 2), Fan Control (Field 3), and Water Pump Control (Field 4).
  6. Obtain the API Key:
  7. After creating the channel, go to the Channel Settings section and copy the Write API Key. This key will be used in the code to send data to ThingSpeak.
  8. Optional: Add Widgets for Visualization:
  9. Under the Apps tab, go to Widgets to add graphical widgets (such as gauges for temperature and humidity) and control widgets for the fan and water pump.

Arduino Code:

#include <WiFi.h>
#include <ThingSpeak.h>
#include <DHT.h>

#define DHTPIN 4 // DHT sensor connected to Pin D4
#define DHTTYPE DHT22 // or DHT11

const char* ssid = "your_SSID"; // Wi-Fi network name
const char* password = "your_PASSWORD"; // Wi-Fi password

unsigned long myChannelNumber = 123456; // Your ThingSpeak Channel Number
const char * myWriteAPIKey = "your_WRITE_API_KEY"; // Your ThingSpeak Write API Key

WiFiClient client;
DHT dht(DHTPIN, DHTTYPE);

int fanPin = 5; // Relay pin for fan
int pumpPin = 18; // Relay pin for water pump

void setup() {
Serial.begin(115200);
WiFi.begin(ssid, password);

// Wait for the WiFi connection
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to WiFi...");
}
Serial.println("Connected to WiFi");

ThingSpeak.begin(client);
dht.begin();
// Set pin modes
pinMode(fanPin, OUTPUT);
pinMode(pumpPin, OUTPUT);
}

void loop() {
float temperature = dht.readTemperature(); // Temperature in Celsius
float humidity = dht.readHumidity(); // Humidity in percentage

// Ensure data is valid
if (isnan(temperature) || isnan(humidity)) {
Serial.println("Failed to read from DHT sensor!");
return;
}

// Display readings in the serial monitor
Serial.print("Temperature: ");
Serial.print(temperature);
Serial.print(" °C ");
Serial.print("Humidity: ");
Serial.print(humidity);
Serial.println(" %");

// Control the fan and water pump based on temperature and humidity
if (temperature > 30) {
digitalWrite(fanPin, HIGH); // Turn on fan if temperature is above 30°C
} else {
digitalWrite(fanPin, LOW); // Turn off fan
}

if (humidity < 50) {
digitalWrite(pumpPin, HIGH); // Turn on water pump if humidity is below 50%
} else {
digitalWrite(pumpPin, LOW); // Turn off water pump
}

// Upload data to ThingSpeak
ThingSpeak.setField(1, temperature); // Temperature data
ThingSpeak.setField(2, humidity); // Humidity data
ThingSpeak.setField(3, (digitalRead(fanPin) == HIGH) ? "ON" : "OFF"); // Fan status
ThingSpeak.setField(4, (digitalRead(pumpPin) == HIGH) ? "ON" : "OFF"); // Water pump status
ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey); // Write data to ThingSpeak

// Wait 30 seconds before sending the next update
delay(30000);
}

Testing and Calibration:

  1. Upload the Code:
  2. Open the Arduino IDE, paste the code, and upload it to your ESP32.
  3. Monitor Serial Output:
  4. Open the Serial Monitor in the Arduino IDE to view the temperature and humidity readings. It will display values like:
Temperature: 28.4 °C
Humidity: 65.2 %
  1. Check ThingSpeak:
  2. Go to your ThingSpeak account and check the live data feed. You should see real-time updates for temperature, humidity, and device control (fan and pump).
  3. The fan and water pump should automatically turn on/off based on the conditions.

Manual Control:

If you have added a push button, you can wire it to control the fan or water pump manually. When pressed, the button can toggle the fan or pump status on the ThingSpeak platform.

Conclusion:

This ESP32-based Smart Greenhouse Control project allows you to:

  1. Monitor temperature and humidity in real-time using ThingSpeak.
  2. Automatically control a fan and water pump to maintain ideal greenhouse conditions.
  3. Optionally visualize the data using ThingSpeak widgets or add manual control using a push button.

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