2.2.3 DHT-11¶

Introduction¶

The digital temperature and humidity sensor DHT11 is a composite sensor that contains a calibrated digital signal output of temperature and humidity. The technology of a dedicated digital modules collection and the technology of the temperature and humidity sensing are applied to ensure that the product has high reliability and excellent stability.

The sensors include a wet element resistive sensor and a NTC temperature sensor and they are connected to a high performance 8-bit microcontroller.

Required Components¶

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Raphael Kit	337	Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
GPIO Extension Board	BUY
Breadboard	BUY
Jumper Wires	BUY
Resistor	BUY
Humiture Sensor Module	BUY

Schematic Diagram¶

Experimental Procedures¶

Step 1: Build the circuit.

Step 2: Go to the folder of the code.

cd ~/raphael-kit/nodejs/

Step 3: Install dependencies.

sudo npm install node-dht-sensor

Step 4: Run the code.

sudo node dht11.js

After the code runs, the program will print the temperature and humidity detected by DHT11 on the computer screen.

Code

var sensor = require("node-dht-sensor");

setInterval(function(){
  sensor.read(11, 17, function(err, temperature, humidity) {
    if (!err) {
      console.log(`temp: ${temperature}\`C, humidity: ${humidity}%`);
    }
  });
},1000);

Code Explanation

var sensor = require("node-dht-sensor");

Import the module node-dht-sensor module, which provides functions for us to read the value of DHT-11.

Note

For more details, please refer to: https://www.npmjs.com/package/node-dht-sensor

sensor.read(11, 17, function(err, temperature, humidity){...})

The node-dht-sensor module provides the read() function for us to read the measured temperature and humidity, where 11 means DHT-11, 17 means and its connected to GPIO17.

if (!err) {
  console.log(`temp: ${temperature}\`C, humidity: ${humidity}%`);
}

When there is no error in the reading, the temperature and humidity values are printed on the terminal.