Humidity & Temperature Basic Sensor DHT11

The DHT11 is a basic digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed). Its fairly simple to use, but requires careful timing to grab data. The only real downside of this sensor is you can only get new data from it once every 2 seconds, so when using our library, sensor readings can be up to 2 seconds old.

Features

• Supply Voltage: DC 3.5 - 5.5V
• Output Signal: digital signal via single-bus
• Operating Range and Accuracy (Humidity): 20-80% RH; +/-5% RH
• Operating Range and Accuracy (Temperature): 0 to 50 C; +/-2% C
• Average Sending Period: 2 seconds
• Dimensions (excluding pins): 12.6mm length x 5.83mm width x 16mm height
• Weight: 2.4g (0.08oz)

Compared to the DHT22, this sensor is less precise, less accurate and works in a smaller range of temperature/humidity, but its smaller and less expensive

A 4.7K or 10K resistor is required, for use as a pullup from the data pin to VCC.

Below is an Arduino example sketch to connect and display temperature in 16 x 02 LCD display:

Connect DATA pin to Arduino analog A0-pin

#include <Wire.h> // builtin library
#include <LiquidCrystal.h> // builtin library
LiquidCrystal lcd(8, 9, 4, 5, 6, 7); // sainsmart 1602 lcd

#include <dht11.h> // download this from http://playground.arduino.cc/main/DHT11Lib
dht11 DHT;

void setup(){
  lcd.begin(16, 2);
}

void loop(){
  DHT.read(A5);
  lcd.print(DHT.temperature); // Celsius output
 
  delay(1000); // DHT11 can't poll faster than 1x a second
}