I can't get data from DHT11

Need Help With My Project
1

Hello,
I’m new in Blynk and I love this program because it can send emails! I want to make a simple program : reading data from a DHT11. I ran DHT11 , I ran ./blynk-ser.sh to connect to blynk server, but you wait and wait and it doesn’t connect to server. I’m using linux. Here is the code:

/*************************************************************
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 value can be pushed from Arduino to
the Blynk App.

WARNING :
For this example you’ll need SimpleTimer library:
https://github.com/jfturcot/SimpleTimer
and Adafruit DHT sensor libraries:
https://github.com/adafruit/DHT-sensor-library

App project setup:
Value Display widget attached to V5
Value Display widget attached to V6
*************************************************************/

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial
#include <SPI.h>
#include <BlynkSimpleSerial.h>
#include <SimpleTimer.h>
#include <DHT.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = " 3c37e93440b04319b8d0bab86cfaa497";

#define DHTPIN A0 // 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;

// 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
Serial.begin(9600);

Blynk.begin(auth);

dht.begin();

// Setup a function to be called every second
timer.setInterval(1000L, sendSensor);
}

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

If anybody can help me , please write here.
Regards,
your Blynk user

2

Welcome @Matei.

AO is an analogue pin, change to a digital pin but ensure you get the numbering correct.

Don’t post unformatted code the forum, see the guidelines for formatting.

3

ok :slight_smile: :

/**************************************************************
  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>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = " 3c37e93440b04319b8d0bab86cfaa497";

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);
}

void loop()
{
  Blynk.run();
}
4

oh , wrong code :grin: :

/*************************************************************
  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 value can be pushed from Arduino to
  the Blynk App.

  WARNING :
  For this example you'll need SimpleTimer library:
    https://github.com/jfturcot/SimpleTimer
  and Adafruit DHT sensor libraries:
    https://github.com/adafruit/Adafruit_Sensor
    https://github.com/adafruit/DHT-sensor-library

  App project setup:
    Value Display widget attached to V5
    Value Display widget attached to V6
 *************************************************************/

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial
#include <SPI.h>
#include <BlynkSimpleSerial.h>
#include <SimpleTimer.h>
#include <DHT.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = " 3c37e93440b04319b8d0bab86cfaa497";

#define DHTPIN A0          // 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;

// 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
  Serial.begin(9600);
  
  Blynk.begin(auth);

  dht.begin();

  // Setup a function to be called every second
  timer.setInterval(1000L, sendSensor);
}

void loop()
{
  Blynk.run();
  timer.run(); // Initiates SimpleTimer
}
5

Do you connected with the basic sketch?

You just need to add DHT once the basic sketch is confirmed as connecting to the server.

Lots of DHT posts on this site for you to look through.

6

Yes , I connected with the basic sketch
P.S: I can try! Good idea!

7

I tried and the code doesn’t work:

#define BLYNK_PRINT Serial
#include <SPI.h>
#include <BlynkSimpleSerial.h>
#include <SimpleTimer.h>
#include <DHT.h>
#define BLYNK_PRINT DebugSerial
#include <BlynkSimpleStream.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = " 3c37e93440b04319b8d0bab86cfaa497";
#define DHTPIN 5  
#define DHTTYPE DHT11 
DHT dht(DHTPIN, DHTTYPE);
SimpleTimer timer;

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


  // Blynk will work through Serial
  // Do not read or write this serial manually in your sketch
  Serial.begin(9600);
  Blynk.begin(auth);
  dht.begin();
  timer.setInterval(1000L, sendSensor);
}

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

Error message:
Arduino: 1.8.1 (Linux), Board: “Arduino/Genuino Uno”

Error compiling for board Arduino/Genuino Uno.

8

So much code. Go back and edit your posts. I want to see a basic sketch that connects to Blynk and your DHT sketch that doesn’t connect to Blynk.

9

Basic:

/**************************************************************
  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>

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

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);
}

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

dht11:

/*************************************************************
  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 value can be pushed from Arduino to
  the Blynk App.

  WARNING :
  For this example you'll need SimpleTimer library:
    https://github.com/jfturcot/SimpleTimer
  and Adafruit DHT sensor libraries:
    https://github.com/adafruit/Adafruit_Sensor
    https://github.com/adafruit/DHT-sensor-library

  App project setup:
    Value Display widget attached to V5
    Value Display widget attached to V6
 *************************************************************/

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial
#include <SPI.h>
#include <BlynkSimpleSerial.h>
#include <SimpleTimer.h>
#include <DHT.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = " 3c37e93440b04319b8d0bab86cfaa497";

#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;

// 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
  Serial.begin(9600);
  
  Blynk.begin(auth);

  dht.begin();

  // Setup a function to be called every second
  timer.setInterval(1000L, sendSensor);
}

void loop()
{
  Blynk.run();
  timer.run(); // Initiates SimpleTimer
}
10

You can’t just take someone else’s sketch that is connecting in a different way and expect it to work with your way (USB).

So you keep all the USB stuff as per good sketch and just add DHT related stuff.
Try this (USB + DHT)

/**************************************************************
  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
}
11

It worked !!! Thanks a lot Costas! :slight_smile: