Published May 8, 2017 © GPL3+

Blynk App with Linkit7688 Duo and Webcam

How to make a functional application with Blynk and the Linkit Smart 7688 Duo board, with utility for home automation.

IntermediateFull instructions provided6 hours3,148

Things used in this project

Hardware components

DHT22 Temperature Sensor

Breadboard (generic)

LED (generic)

Jumper wires (generic)

RobotGeek Relay

USB-A to Micro-USB Cable

Buzzer

Resistor 330 ohm

Resistor 10k ohm

Camera (generic)

Software apps and online services

Arduino IDE

Blynk

Story

The idea

I am doing an automation project as the final work of automation in the university. The goal is to make a home system with an application; in this case, we will use the Blynk platform due to its ease of use and its ability to communicate with the Linkit Smart 7688 Duo board. We will also implement a camera that can be used for home security.

Steps

Create Blynk Account

First you have to download the Blynk app in the Google app store:

Blynk App

Then create a new account:

Next step is to create a new project:

Create example

You must choose the device you should work with.

In this case, it is of vital importance to choose "Arduino Yun" as the device and "WiFi" as the connection type in order to be able to connect with Linkit Smart 7688 Duo.

Create example

Then a screen like the one below will appear where Blynk will send an email with the data to register your device.

Blynk email sent example

Auth Token

In the email comes the Auth Token. That is used for the Arduino code and its connection in Blynk. Also, there comes a link with the Sketch Generator that serves to obtain the code to upload to our board Linkit Smart 7688 Duo.

Email Blynk Example

Sketch Generator

In the Sketch Generator, you have to choose "Arduino Yun," the type of connection "YunBridge" and write your Auth Token, and the code will be generated automatically. You can copy it and paste it in Arduino IDE and upload it to the Linkit 7688 board.

Blynk Example web

To upload a sketch to the Linkit Smart 7688 Duo board, you can see the following tutorial where it is explained very well: tutorial.

Display

The application has two tables to display the value of the humidity and temperature sensors, and 4 buttons to turn on and off the LEDs connected to the 4-channel relay module.

When any button is lit, it can be displayed as follows:

The Various Codes

Webcam Code

I used the Bridge and Process libraries to communicate with the processor so I can make Python programs that will control my webcam.

Libraries that i used

Sensor Code

I was going to use the DHT22 sensor, for that reason the code includes the library of the sensor and also uses the timer of the Blynk platform to send the readings of the sensor.

DHT libraries and BlynkTimer

Temperature and Humidity Code

I used 3 functions; the first was to perform the reading of the temperature and humidity sensor.

Sensor reading function

Webcam "Take Picture" Code

Then there is a function to control the web camera from the terminal using the processing library. The example of this you can see in the following link:

https://www.twilio.com/blog/2015/02/arduino-powered-photobooth-arduino-yun-a-webcam-and-dropbox.html

Functions to take a send a picture to Dropbox

Setup Code

In the Setup function, we initialize the bridge, Blynk, the DHT22 sensor, the serial communication and the timer, as well as define LED as an output that will be the alarm with the buzzer that we will use later.

Setup function

Loop Function Code

Finally, we have the loop function that activates the communication between Blynk and the LinkitSmart 7688 Duo. It also starts the timer to count the values of the sensors, then reads the value of the Monitor Series. In this example, when sending the value of "1", it triggers the routine that activates the buzzer, sends an email to the user using the function Blynk.email and takes and sends the photograph.

You can change the value of the serial monitor by the value of a sensor, preferably the PIR HC-SR501 sensor, but I do not currently have that sensor and my project is by way of demonstration.

PIR Sensor is optional

Dropbox Code

The Python code for sending it to Dropbox is as follows:

import dropbox
import datetime 
suffix = datetime.datetime.now().strftime("%Y-%m-%d-%H-%M-%S")
filename = "photobooth-" + suffix + ".jpg" 
client = dropbox.client.DropboxClient('YOURACCESSTOKENGOESHERE')
f = open('/mnt/sda1/pic.jpg', 'rb')
response = client.put_file(filename, f)
print "uploaded:", response

Results

Relay Module and LED´s

Relay module and buzzer

Linkit Smart 7688 Duo and DHT22 sensor

Blink Operation

In the following video, I show the operation of the application of Blynk and turn on and off the LEDs.

Example 1

In the following video, I show the operation of the application of Blynk and send the value of "1" by the serial monitor so that the camera takes a photo and automatically sends it to Dropbox. You can improve the example using any sensor.

Example 2

I hope you can make your own version; and if you have any questions with the project, I can help you.

The project works for both the Linkit Smart 7688 Duo and the Arduino Yun.

Code

#define BLYNK_PRINT Serial
/* Set this to a bigger number, to enable sending longer messages */
//#define BLYNK_MAX_SENDBYTES 128
#include <Bridge.h>
#include <Process.h>
#include <BlynkSimpleYun.h>

char auth[] = "755c4016d214484480b80c5739068ef7";
byte b=0,c=0,d=0,e=0;
char a;
int LED = 5 ;

#include <DHT.h>
#define DHTPIN 6          // What digital pin we're connected to
#define DHTTYPE DHT22   // DHT 22, AM2302, AM2321
//#define DHTTYPE DHT21   // DHT 21, AM2301

DHT dht(DHTPIN, DHTTYPE);
BlynkTimer 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() {
  // put your setup code here, to run once:
  Bridge.begin();
  Blynk.begin(auth);
  dht.begin();
  timer.setInterval(1000L, sendSensor);
  pinMode(LED, OUTPUT);
  digitalWrite(LED, LOW);
  Serial.begin(9600);
  Serial.print("Hola, para tomar una foto favor de mandar un 1");
  

}

void loop() {
  // put your main code here, to run repeatedly:
  Blynk.run();
  timer.run();
  a=Serial.read();
  if(a=='1')
  {
  digitalWrite(LED, HIGH); 
  Blynk.email("pufyx1@gmail.com", "Intruso", "Hay alguien inesperado en la casa, revisa la foto en dropbox"); 
  takePicture();
  uploadPicture();
  a=0;  
  digitalWrite(LED, LOW);  
  }
}


void takePicture() {
  Process p; // Create a new process
  p.begin("fswebcam"); // Run the fswebcam utility, but first...
  p.addParameter("/root/app/pic.jpg"); // add a path parameter
  p.addParameter("-r 1280x720"); // and a resolution parameter
  p.run(); // now run it and and wait for its termination
}

void uploadPicture() {
  Process p; 
  p.begin("python"); 
  p.addParameter("/root/app/dropy.py"); 
  p.run(); 
}

Credits

Alexis Santiago Allende

0 projects • 73 followers

Im a person who since young feel a passion for electronics, I also like to cook pizza and travel. Now Im working on the internet of things

Blynk App with Linkit7688 Duo and Webcam

Things used in this project

Hardware components

Software apps and online services

Story

The idea

Steps

Auth Token

Sketch Generator

Display

The Various Codes

Results

Blink Operation

Schematics

My circuit

Code

Blynk Bridge DHT22

Send photo

Credits

Alexis Santiago Allende

Comments

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Blynk App with Linkit7688 Duo and Webcam

Blynk App with Linkit7688 Duo and Webcam

Things used in this project

Hardware components

Software apps and online services

Story

The idea

Steps

Auth Token

Sketch Generator

Display

The Various Codes

Results

Blink Operation

Schematics

My circuit

Code

Blynk Bridge DHT22

Send photo

Credits

Alexis Santiago Allende

Comments

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