Arduino Uno Temperature and Humidity Reading with DHT-11 Sensor

DHT-11 is a temperature and humidity sensor module. It use a serial data transmission between the module and the controller. It has the following features:

• Operating Voltage: 3.5V to 5.5V
• Operating current: 0.3mA (measuring) 60uA (standby)
• Output: Serial data
• Temperature Range: 0°C to 50°C
• Humidity Range: 20% to 90%
• Resolution: Temperature and Humidity both are 16-bit
• Accuracy: ±1°C and ±1%

A simple DHT-11 Sensor

It's suitable for in-house temperature controlling, or the irrigation system. This module is very popular to apply with the Arduino. The DATA pin of this module is the serial data I/O pin. It requires an additional pull up resistor, typically a 5kOhm resistor.

Typical connection

In this example, the Arduino Uno will read the environmental data from this module, and it will show on a character display. The LCD I use here is a 16x2 character LCD. I use an additional PCF8574T I2C to parallel I/O to the LCD.

Arduino running program

The pull up resistor I used here is 10kOhm.

//Two-Wire library
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
//DHT-11 Sensor Library
#include <SimpleDHT.h>
 
//Default address 0x27, LCD is 16x4
LiquidCrystal_I2C lcd(0x27,16,4);
 
//DHT-11 connects to pin A0
SimpleDHT11 dht11(A0);
 
void setup(){
  //Initialize the LCD
  lcd.init();
  //Turn on the backlight
  lcd.backlight();
 
  //show some information
  lcd.print("BTE Technician");
  lcd.setCursor(0,1);
  lcd.print("Arduino Uno And");
  lcd.setCursor(-4,2);
  lcd.print("DHT-11 Sensor");
  lcd.setCursor(-4,3);
  lcd.print("LCD Example");
  delay(3000);
  lcd.clear();
}
 
byte temperature,humidity;
 
void loop(){
  //Get temperature, humidity, and no raw data
  dht11.read(&temperature,&humidity,NULL);
 
  lcd.setCursor(0,0);
  lcd.print("Temperature:");
 
  lcd.setCursor(3,1);
  lcd.print(String(temperature,DEC)+" "+char(223)+"C");
 
  lcd.setCursor(-4,2);
  lcd.print("Humidity:");
 
  lcd.setCursor(-1,3);
  lcd.print(String(humidity,DEC)+" %RH");
  delay(3000);
}

Its wiring diagram is shown below.

Wiring diagram

Click here to download its source file.