Blynk for NodeMCU – Reading DHT-11 sensor data on Blynk App remotely.

This tutorial of Robo India explains how to upload the data using the NodeMCU, to show the temperature and humidity DHT11 sensor on your Smartphone or tablet on Blynk App. 

1. Introduction:

In this project using an esp8266, to show the temperature and humidity DHT11 sensor on your Smartphone or tablet. The NodeMCU collects the temperature and humidity from DHT11 sensor and sends it to Blynk app every second.

1.2 Hardware required

Blynk Board and NodeMCU is used in this example. Inset NodeMCU to the Blynk board as shown in the image ahead then connect NodeMCU to PC or Laptop through USB cable.

2. On Blynk App

You need to perform following steps on Blynk App.

2.1 Create a New Project in BLYNK app.Write Project name Temperature Humidity and Select NodeMCU from drop down.

2.2 An AUTH token will be sent to your registered email, note this down. Tap on the screen and add a 2 Gauges.

2.3 Tap on the Widget and select the respective Virtual pins for temperature and humidity data (V0 for temperature and V1 for humidity).

Note: Make sure to setup Reading rate as ‘1’ second for all Widgets. And add gauges for both Humidity and Temperature.

3. Code the NodeMCU with the following code.

Before uploading, make sure to paste your authorization token into the auth [] variable. Also make sure to load your Wifi network settings into the Blynk.begin(auth, “ssid”, “pass”) function.

Following code may be downloaded from here.

// Robo India Tutorial 
// Digital Output on LED 
// Hardware: NodeMCU Blynk Board


#define BLYNK_PRINT Serial


#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include "DHT.h"           // including the library of DHT11 temperature and humidity sensor
#include <SimpleTimer.h>   //including the library of SimpleTimer
#define DHTTYPE DHT11      // DHT 11

#define dht_dpin 14
DHT dht(dht_dpin, DHTTYPE); 
SimpleTimer timer;
char auth[] = "Your Auth. Key";            // You should get Auth Token in the Blynk App.
                                           // Go to the Project Settings (nut icon).

char ssid[] = "Your Wifi Network name";    // Your WiFi credentials.
char pass[] = "Password of your network";  // Set password to "" for open networks.
float t;                                   // Declare the variables 
float h;



void setup()
{
    Serial.begin(9600);// Debug console
    Blynk.begin(auth, ssid, pass);
    dht.begin();
    timer.setInterval(2000, sendUptime);
}

void sendUptime()
{
  
  float h = dht.readHumidity();
  float t = dht.readTemperature(); 
  Serial.println("Humidity and temperature\n\n");
  Serial.print("Current humidity = ");
  Serial.print(h);
  Serial.print("%  ");
  Serial.print("temperature = ");
  Serial.print(t); 
  Blynk.virtualWrite(V0, t);
  Blynk.virtualWrite(V1, h);
  
}

void loop()
{
  Blynk.run();
  timer.run();
}

4. Output

After Uploading the Ardunio code IDE. Press the play button on blynk app to show the output.

5. Where to buy.

Buy this kit on Amazon: 

Buy this kit on Robo India: click here

Thanks and Regards
Content Development Team 
Robo India
https://roboindia.com