Tech with Matthew
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How to read temperature and humidity on Blynk with DHT11

A DHT11 connected to Blynk to read data

IntermediateFull instructions provided30 minutes18,404
How to read temperature and humidity on Blynk with DHT11

Things used in this project

Hardware components

DHT11 Temperature & Humidity Sensor (4 pins)
DHT11 Temperature & Humidity Sensor (4 pins)
×1
Jumper wires (generic)
Jumper wires (generic)
×1
Arduino UNO & Genuino UNO
Arduino UNO & Genuino UNO
×1
Android device
Android device
×1

Software apps and online services

Arduino IDE
Arduino IDE
Blynk
Blynk

Story

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Schematics

DHT11

Sorry but I didn't find a DHT11 so I renamed a TMP36 to DHT11

Code

Code for DHT11

C/C++
/**************************************************************
  Blynk is a platform with iOS and Android apps to control
  Arduino, Raspberry Pi and the likes over the Internet.
  You can easily build graphic interfaces for all your
  projects by simply dragging and dropping widgets.
    Downloads, docs, tutorials: http://www.blynk.cc
    Blynk community:            http://community.blynk.cc
    Social networks:            http://www.fb.com/blynkapp
                                http://twitter.com/blynk_app
  Blynk library is licensed under MIT license
  This example code is in public domain.
 *************************************************************
  This example shows how to use ordinary Arduino Serial
  to connect your project to Blynk.
  Feel free to apply it to any other example. It's simple!
 *************************************************************
             USB HOWTO: http://tiny.cc/BlynkUSB
 **************************************************************/

// You could use a spare Hardware Serial on boards that have it (like Mega)
#include <SoftwareSerial.h>
SoftwareSerial DebugSerial(2, 3); // RX, TX

#define BLYNK_PRINT DebugSerial
#include <BlynkSimpleStream.h>

#include <SimpleTimer.h>
#include <DHT.h>
#define DHTPIN 5          // What digital pin we're connected to

// Uncomment whatever type you're using!
#define DHTTYPE DHT11     // DHT 11
//#define DHTTYPE DHT22   // DHT 22, AM2302, AM2321
//#define DHTTYPE DHT21   // DHT 21, AM2301

DHT dht(DHTPIN, DHTTYPE);
SimpleTimer timer;

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "YourAuthToken";

// This function sends Arduino's up time every second to Virtual Pin (5).
// In the app, Widget's reading frequency should be set to PUSH. This means
// that you define how often to send data to Blynk App.

void sendSensor()
{
  float h = dht.readHumidity();
  float t = dht.readTemperature(); // or dht.readTemperature(true) for Fahrenheit

  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  // You can send any value at any time.
  // Please don't send more that 10 values per second.
  Blynk.virtualWrite(V5, h);
  Blynk.virtualWrite(V6, t);
}

void setup()
{
  // Debug console
  DebugSerial.begin(9600);

  // Blynk will work through Serial
  // Do not read or write this serial manually in your sketch
  Serial.begin(9600);
  Blynk.begin(Serial, auth);
    // Setup a function to be called every second
  timer.setInterval(1000L, sendSensor);
}

void loop()
{
  Blynk.run();
  timer.run(); // Initiates SimpleTimer
}

Credits

Tech with Matthew

Tech with Matthew

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