IoT Based Humidity and Temperature Logging

Hey Folks,
In this tutorial, we will learn, how to interface DHT 11 with Node Mcu(ESP8266). 
The DHT11 is a basic, ultra low-cost 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).

DHT11 Back Side

DHT11-Internal Sensor

Components Required

• NodeMcu(ESP8266) 
• DHT 11 SENSOR 
• Few male to female connecting wires 
• Breadboard

Follow the image below for circuit connection reference.

DHT11 Sensor connection with NodeMCU(WiFi-Module)

In this circuit, we have connected the output pin to the D3 pin of the NodeMcu module and NC pin remain disconnected.

After making the circuit dump the code given below.

// Karkhana Report
// temperature and humidity data using thingspeak.com
// Hardware: NodeMCU,DHT11
#include <DHT.h> // Including library for dht
#include <ESP8266WiFi.h>
String apiKey = "THINGSPEAK API KEY"; // Enter your Write API key from ThingSpeak
const char *ssid = "ENTER YOUR SSID"; // replace with your wifi ssid and wpa2 key
const char *pass = "ENTER YOUR PASSWORD";
const char* server = "api.thingspeak.com";
#define DHTPIN 0 //pin where the dht11 is connected
DHT dht(DHTPIN, DHT11);
WiFiClient client;
void setup()
{
Serial.begin(115200);
delay(10);
dht.begin();
Serial.println("Connecting to Karkhana Wifi");
Serial.println(ssid);
WiFi.begin(ssid, pass);
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected to Karkhana");
}
void loop()
{
float h = dht.readHumidity();
float t = dht.readTemperature();
if (isnan(h) || isnan(t))
{
Serial.println("Failed to read from DHT sensor of Karkhana!");
return;
}
if (client.connect(server, 80)) // "184.106.153.149" or api.thingspeak.com
{
String postStr = apiKey;
postStr += "&field1=";
postStr += String(t);
postStr += "&field2=";
postStr += String(h);
postStr += "\r\n\r\n";
client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(postStr.length());
client.print("\n\n");
client.print(postStr);
Serial.print("Temperature: ");
Serial.print(t);
Serial.print(" degrees Celcius, Humidity: ");
Serial.print(h);
Serial.println("%. Send to Thingspeak.");
}
client.stop();
Serial.println("Waiting...");
// thingspeak needs minimum 15 sec delay between updates, i've set it to 30 seconds
delay(3000);
}

After dumping the code we can check our output in the serial monitor as well as in the thingspeak blogging channel chart graphically as shown below:-

As you can see from the above logging figure we can check the humidity and temperature rate of Karkhana.

Thinking?

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