Published February 4, 2021 © GPL3+

A step to use Blynk for IoT!

Practising IoT using DHT11 Sensor and LDR Sensor for sending data to Blynk!

BeginnerShowcase (no instructions)900

Things used in this project

Hardware components

NodeMCU ESP8266 Breakout Board

Mine is black, though.

DFRobot Gravity: DHT11 Temperature Humidity Sensor For Arduino

Mine is a cheaper one :)

LDR Module

I've used a LDR module, but again, you can just use a plain LDR component with a resistor, google it

Jumper wires (generic)

Micro-USB to USB Cable (Generic)

Used for programming NodeMCU.

Breadboard (generic)

Any breadboard will do it

Software apps and online services

Blynk

You can setup your own Blynk server: https://github.com/blynkkk/blynk-server

Hand tools and fabrication machines

Smartphone

To use Blynk app

Story

This project is about learning how to send data to a Blynk server [any Blynk server, in my case, I've prepared my own Blynk server using open source Blynk server :), but you can use official one]. I decided to make it because, well, its enjoying :) Second, I wanted to prepare a project that can monitor my room for testing purposes.

Here is a screenshot from Blynk:

Screenshot from Blynk app! Actually I've set my own server as a Blynk app, to achive unlimited energy :)

The project is basically about a NodeMCU board that sents light, humidity and temperature information of the room. And the server (your own server, or official Blynk server), process the data and sends back to your mobile device! It is not something professional but entertaining, I believe (and enjoying :) ).

Here is the diagram of the work:

Diagram of the small project.

Note that I didn't use that breadboard, because I wanted to fit NodeMCU into breadboard so since I couldn't do this with that breadboard, instead, I've used two small breadboard. But the connections are same.

Another note, I've used D6 pin for DHT11 sensor, which corresponds to GPIO12 pin. So please don't confuse pin number, you should write 12 in code to use D6 pin. Not six...

Another note about LDR module, you might not have module but instead LDR component's itself, you will just need to connect a resistor to use it, you don't need to buy a module for that. Google it!

You can develop the code and add more things! I've tried my best to explain thins with comments lines.

You can add the GUI parts in Blynk app like I did in photos (Don't forget that if you don't own your own Blynk server, you will have limited energy like 2000. In this case, you might not be able to use many components in the app. You can use "Labeled Values" component instead of "SuperChart" component in this case:

Widget Box, you can find there from the top gear icon

Adding data stream to graphs.

Configuring input for the datastream.

Enjoy it!

Code

/* This is the main file which should has a name of "sketch_XXX.ino" */
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include "DHT.h"

/* Replace DHTSensorPin's value (which is 12) with your GPIO pin! :) */
#define DHTSensorPin 12

/* You should choose DHT22 instead if you got DHT22. */
#define DHTType DHT11

DHT dht(DHTSensorPin, DHTType);

int minimumDhtSamplePeriod;

/* Prototypes */
void wifiSetup();
void cloudSetup();

/*
 * You can get this token from your e-mail! Don't forget, it's a secret! Keep it secure.
 */
char token[] = "XXXXXXXXXXXXXX";

/*
 * Wifi configuration to connect.
 */
char ssid[] = "SSID_HERE";
char pass[] = "PASSWORD_HERE";

void setup() {
  Serial.begin(9600);

  wifiSetup();
  cloudSetup();

  dht.begin();
  minimumDhtSamplePeriod = 2000;
}

void loop() {
  /* You can put another code there, but please don't use delay as much you can (you still can use for small values, like 50 micro seconds) */
  cloudLoop();
  programLoop();
}

/*
 * Init wifi
 */
void wifiSetup() {
 
  WiFi.begin(ssid, pass); 
  while (WiFi.status() != WL_CONNECTED) {
    Serial.println("Trying to reconnect...");
    delay(2000);
  }

  Serial.println("WiFi connected!");
}

/* ---------------- CLOUD FUNCTIONS ----------------- */
void cloudSetup() {
  // Blynk.begin(auth, ssid, pass...) wasn't used because I wanted to make cloud and wifi functions seperate.
  Blynk.config(token); /* You can use Blynk.config(token, "XXX.XXX.XXX.XXX", PORT_NUMBER); format if you want to install Blynk server into your own VPS. (Default port is 8080) */

  
  while(Blynk.connect() == false) {
    Serial.println("Trying to reconnect to Blynk again");
    delay(2000);  
  }

  Serial.println("Connected to Blynk!");
}

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

/* Don't forget to include this file too! If you can't add more file, you should add this into end of "sketch_XXX.ino" file :) */
int timePassed = millis();


void programLoop() {
  float temp, humidity, light;
  if (millis() - timePassed > minimumDhtSamplePeriod) {
    
    humidity = dht.readHumidity();
    temp = dht.readTemperature();
    timePassed = millis();
    
    if (isnan(humidity) || isnan(temp)) {
      Serial.println("An error occured");
      return;
    }

    light = 1024 - analogRead(A0);
    Blynk.virtualWrite(V2, temp);
    Blynk.virtualWrite(V3, humidity);
    Blynk.virtualWrite(V4, light);
  }
}

Credits

selimrecep

0 projects • 2 followers

A step to use Blynk for IoT!

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Schematics

The general diagram

Code

sketch.ino

main.ino

DHT-sensor-library

Credits

selimrecep

Comments

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A step to use Blynk for IoT!

A step to use Blynk for IoT!

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Schematics

The general diagram

Code

sketch.ino

main.ino

DHT-sensor-library

Credits

selimrecep

Comments

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