Let's Workshop: Keyes DHT11 Temperature and Humidity Module


Here is a quick introduction to using the Keyes DHT11 Temperature and humidity module. Hopefully it will provide you with the confidence to integrate climate sensing into your project.

This example will demonstrate the use of an Arduino UNO reading byte data from the sensor. Once connected and the program loaded, it will read the temperature and humidity, every second and a half (the sensor has a refreshes it's reading every second). This will use the SimpleDHT library library created by Winlin.

Components

  • 1pcs Arduino UNO or Compatible - LCAA100005
  • 1pcs Keyes DHT11 Temperature and Humidity Sensor Module - BDAA100058
  • 3pcs Male to Female Jumper Cables - GBAA100002

Wiring

Wire the two boards together as can be seen in the image below, taking care to match the pin numbers.

Coding

The code consists of an include, definitions, initilisation, setup and loop. First the SimpleDHT library is linked to the code. This is followed by the initilisation of the sensor object used by the library and the pin it is connected to. The setup initilises the serial connection. The loop requests the temperature and humidity from the library, storing it in the byte variables declared. The values are then output to the serial connection, pausing for a moment and repeating.

Load the code below into the Arduino IDE and upload it to your board.

/*
  A simple program designed to setup and demonstrate the SimpleDHT library and 
  Keyes DHT11 Temperature and Humiditiy Module - BDAA100058

  The program uses the SimpleDHT library to interface with the module
  and return a temperature and humidity to the serial monitor. Then repeat the request. 
  
  modified 31 May 2019
  by Sebastian Karam - Flux Workshop
  
  The SimpleDHT library created by Winlin
  https://github.com/winlinvip/SimpleDHT
*/ 
#include   // include the SimpleDHT library

int sensorPin = 2; // define the pin the sensor is connected to
SimpleDHT11 dht11Sensor(sensorPin); // create the sensor object

void setup() {
  Serial.begin(9600); // initialise the serial connection  
}

void loop() {
  byte temperature = 0; // define a variable to store the temperature
  byte humidity = 0; // define a variable to store the humidity
  dht11Sensor.read(&temperature, &humidity, NULL); // read the values from the DHT11
  Serial.println("-------------------");
  Serial.println((String)"Temperature: " + (int)temperature + "degC"); // send the result to the serial monitor
  Serial.println((String)"Humidity: " + (int)humidity + "%"); // send the result to the serial monitor
  delay(1500); // pause for a moment before repeating
}

Running

With the board loaded with the program and all the connections made, start the serial monitor. An initial value for the temperature and humidity will appear. The output should be as seen below (in this instance, held free, then moist air blown momentarily across it).

What to try next?

  • Output the values to an LCD screen.
  • Mount the sensor in a sheltered container outside and relay the information on to provide a weather report.
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