DHT11 LM35 Temperature Humidity Sensor Expansion Board User’s Guide

Overview

The DHT11 LM35 Temperature Humidity Sensor Expansion Board is an Arduino-compatible shield that combines multiple sensors and components for easy prototyping. It includes:

• DHT11 digital temperature & humidity sensor
• LM35D analog temperature sensor
• 2-way button & 2-way LED
• Passive buzzer
• Rotary potentiometer
• Full-color LED
• IR receiver
• LDR (light-dependent resistor) sensor
• I2C interface (A4 SDA, A5 SCL)
• TTL serial port
• Digital ports (D7, D8)
• Analog port (A3)

Pinout & Connections

Setup Instructions

1. Mount the board directly onto your Arduino Uno or compatible board.
2. Power supply: 5V via Arduino’s VCC and GND.
3. Connect sensors:
   • DHT11 → Digital pin (DATA) with pull-up resistor (if not onboard).
   • LM35D → Analog pin A3.
4. Optional peripherals: Use buttons, LEDs, buzzer, and potentiometer for interactive projects.

Programming Guide

Example: Reading DHT11

#include "DHT.h"
#define DHTPIN 7
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
}

void loop() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  Serial.print("Humidity: "); Serial.print(h);
  Serial.print("%  Temperature: "); Serial.print(t); Serial.println("°C");
  delay(2000);
}

Example: Reading LM35

int lm35Pin = A3;

void setup() {
  Serial.begin(9600);
}

void loop() {
  int value = analogRead(lm35Pin);
  float voltage = value * (5.0 / 1023.0);
  float tempC = voltage * 100; // 10mV per °C
  Serial.print("LM35 Temp: "); Serial.print(tempC); Serial.println("°C");
  delay(1000);
}

Applications

• Weather monitoring station
• Smart home temperature/humidity control
• Educational kits for sensor learning
• IoT projects with multiple sensor inputs

Notes & Tips

• Accuracy: DHT11 ±2°C, ±5% RH; LM35 ±0.5°C.
• Sampling rate: DHT11 updates every 1–2 seconds.
• Avoid long wires (>20cm) for DHT11 to prevent signal loss.
• Use pull-up resistor (5–10kΩ) on DHT11 DATA if not onboard.