Circuit Documentation

Summary

This circuit is designed to monitor temperature and humidity using a DHT11 sensor and an Arduino UNO. The Arduino reads data from the DHT11 sensor and activates a buzzer if the temperature exceeds 30°C. The circuit is powered by a 9V battery connected through a universal barrel jack.

Component List

1. DHT11 Humidity and Temperature Sensor

   • Description: Measures humidity and temperature.
   • Pins: VDD, DATA, NULL, GND

2. Arduino UNO

   • Description: Microcontroller board based on the ATmega328P.
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

3. Buzzer

   • Description: Emits sound when activated.
   • Pins: +, GND

4. Universal Barrel Jack Male

   • Description: Connects the 9V battery to the circuit.
   • Pins: Power Out, V+, V-

5. 9V Battery

   • Description: Provides power to the circuit.
   • Pins: -, +

Wiring Details

DHT11 Humidity and Temperature Sensor

• VDD connected to 5V on Arduino UNO
• DATA connected to D2 on Arduino UNO
• GND connected to GND on Arduino UNO

Arduino UNO

• 5V connected to VDD on DHT11 Humidity and Temperature Sensor
• D2 connected to DATA on DHT11 Humidity and Temperature Sensor
• GND connected to GND on DHT11 Humidity and Temperature Sensor
• GND connected to GND on Buzzer
• D8 connected to + on Buzzer

Buzzer

• GND connected to GND on Arduino UNO
• + connected to D8 on Arduino UNO

Universal Barrel Jack Male

• V+ connected to + on 9V Battery
• V- connected to - on 9V Battery

9V Battery

• + connected to V+ on Universal Barrel Jack Male
• - connected to V- on Universal Barrel Jack Male

Code Documentation

#include "DHT.h"

#define DHTPIN 2     // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11   // DHT 11

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  pinMode(8, OUTPUT);
  Serial.begin(9600);
  Serial.println(F("DHTxx test!"));

  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  if(t > 30){
    digitalWrite(8, HIGH);
  }else{
    digitalWrite(8, LOW);
  }

  float hif = dht.computeHeatIndex(f, h);
  float hic = dht.computeHeatIndex(t, h, false);

  Serial.print(F("Humidity: "));
  Serial.print(h);
  Serial.print(F("%  Temperature: "));
  Serial.print(t);
  Serial.print(F("°C "));
  Serial.print(f);
  Serial.print(F("°F  Heat index: "));
  Serial.print(hic);
  Serial.print(F("°C "));
  Serial.print(hif);
  Serial.println(F("°F"));
}

This code initializes the DHT11 sensor and reads the temperature and humidity every 2 seconds. If the temperature exceeds 30°C, the buzzer is activated. The temperature, humidity, and heat index are printed to the serial monitor.