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Flame Alert System with Blynk

In this chapter, we will guide you through the process of creating a home flame alarm system demo using Blynk. By utilizing a flame sensor, you can detect potential fires in your home. Sending the detected values to Blynk allows for remote monitoring of your home via the internet. In case of a fire, Blynk will promptly notify you via email.

1. Build the Circuit

Note

The ESP8266 module requires a high current to provide a stable operating environment, so make sure the 9V battery is plugged in.

• Arduino UNO R4 Minima Board

• Flame Sensor Module

• ESP8266 Module

2. Configure Blynk

2.1 Create template

Firstly, we need to establish a template on Blynk. Follow the steps below to create a “Flame Alert System” template.

Ensure that the HARDWARE is configured as ESP8266 and the CONNECT TYPE is set to WiFi.

2.2 Datastream

Create a Datastream of type Virtual Pin in the Datastream page to get the value of Flame sensor module.

Set the name of the Virtual Pin to flame_sensor_value. Set the DATA TYPE to Integer and MIN and MAX to 0 and 1.

2.3 Event

Next, we will create an event that logs the detection of flames and sends an email notification.

Note

It is recommended to keep it consistent with my settings, otherwise you may need to modify the code to run the project.

Set EVENT NAME to flame_detection_alert. At the same time, you can customize the content of email sent by setting DESCRIPTION for event triggering. You can also set frequency limits for event triggering below.

Go to the Notifications page and configure email settings.

2.4 Web Dashboard

We also need to set up the Web Dashboard to display the sensor data sent from the Uno board.

Drag and drop an Label widget on the Web Dashboard page.

In the settings page of the Label widget, select Datastream as flame_sensor_value(V0). Then set the color of WIDGET BACKGROUND to change with the value of data. When the displayed value is 1, it will be shown in green. When the value is 0, it will be shown in red.

2.5 Save template

At last, remember to save the template.

In case you need to edit the template, you can click on the edit button in the upper right corner.

3. Run the Code

1. Open the 01-Flame_alert_system.ino file under the path of ultimate-sensor-kit\iot_project\wifi\01-Flame_alert_system, or copy this code into Arduino IDE.

2. Create a Blynk device using the Flame Detection Alert template. Then, replace the BLYNK_TEMPLATE_ID, BLYNK_TEMPLATE_NAME, and BLYNK_AUTH_TOKEN with your own.

   #define BLYNK_TEMPLATE_ID "TMPxxxxxxx"
   #define BLYNK_TEMPLATE_NAME "Flame Alert System"
   #define BLYNK_AUTH_TOKEN "xxxxxxxxxxxxx"
   

   

3. You also need to enter the ssid and password of the WiFi you are using.

   char ssid[] = "your_ssid";
   char pass[] = "your_password";
   

4. After selecting the correct board and port, click the Upload button.

5. Open the Serial monitor(set baudrate to 115200) and wait for a prompt such as a successful connection to appear.

   

   Note

   If the message ESP is not responding appears when you connect, please follow these steps.

   • Make sure the 9V battery is plugged in.

   • Reset the ESP8266 module by connecting the pin RST to GND for 1 second, then unplug it.

   • Press the reset button on the R4 board.

   Sometimes, you may need to repeat the above operation 3-5 times, please be patient.

6. Now, Blynk will show the data read from flame sensor. In the label widget, you can see the value read by the flame sensor. When the displayed value is 1, the background of the label will be shown in green. When the value is 0, the background of the label will be shown in red and Blynk will send you an alert email.

7. If you want to use Blynk on mobile devices, please refer to How to use Blynk on mobile device?.

4. Code explanation

1. Library Initialization

   Before we start, it’s crucial to set up the necessary libraries and settings for communication between the Arduino, ESP8266 WiFi module, and Blynk app. This code sets up the required libraries and configures a software serial connection between the Arduino and ESP8266 module, with the appropriate baud rate for data transmission.

   //Set debug prints on Serial Monitor
   #define BLYNK_PRINT Serial
   
   #include <ESP8266_Lib.h>               // Library for ESP8266
   #include <BlynkSimpleShieldEsp8266.h>  // Library for Blynk
   
   // Software Serial on Uno
   #include <SoftwareSerial.h>
   SoftwareSerial EspSerial(2, 3);  // RX, TX
   #define ESP8266_BAUD 115200      // Set the ESP8266 baud rate
   ESP8266 wifi(&EspSerial);
   

2. Blynk and WiFi configuration

   For the project to communicate with the Blynk app, it needs to connect to a Wi-Fi network. The credentials need to specified here.

   // Template ID, Device Name and Auth Token are provided by the Blynk Cloud
   // See the Device Info tab, or Template settings
   #define BLYNK_TEMPLATE_ID "TMPxxxxxx"
   #define BLYNK_TEMPLATE_NAME "Flame Alert System"
   #define BLYNK_AUTH_TOKEN "xxxxxxxxxxxxxxx"
   
   // Your WiFi credentials.
   // Set password to "" for open networks.
   char ssid[] = "your_ssid";
   char pass[] = "your_password";
   

3. Sensor Pin & Timer Declaration

   Define the pin number for the flame. Blynk library provides a built-in timer, and we create a timer object. More about Why we use Blynk timer?

   const int sensorPin = 8;
   BlynkTimer timer;
   

4. setup() Function

   Initial configurations such as setting the pin mode for the sensorPin, initiating serial communication, setting the BlynkTimer, and connecting to the Blynk app are done in this function.

   • We use timer.setInterval(1000L, myTimerEvent) to set the timer interval in setup(), here we set to execute the myTimerEvent() function every 1000ms. You can modify the first parameter of timer.setInterval(1000L, myTimerEvent) to change the interval between myTimerEvent executions.

   
   

   void setup() {
     pinMode(sensorPin, INPUT);
     Serial.begin(115200);
     EspSerial.begin(ESP8266_BAUD);
     delay(1000);
     timer.setInterval(1000L, myTimerEvent);
     Blynk.config(wifi,BLYNK_AUTH_TOKEN);
     Blynk.connectWiFi(ssid, pass);
   }
   

5. loop() Function

   The main loop runs the Blynk and Timer services continuously.

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

6. myTimerEvent() & sendData() Function

   void myTimerEvent() {
     // Please don't send more that 10 values per second.
     sendData();  // Call function to send sensor data to Blynk app
   }
   

   The sendData() function reads the value from the flame sensor and sends it to Blynk. If it detects a flame (value 0), it sends flame_detection_alert event to the Blynk app.

   • Use Blynk.virtualWrite(vPin, value) to send data to virtual pin V0 on Blynk. More about Blynk.virtualWrite() .

   • Use Blynk.logEvent("event_code") to log event to Blynk. More about Blynk.logEvent() .

   
   

   void sendData() {
     int data = digitalRead(sensorPin);
     Blynk.virtualWrite(V0, data);  // send data to virtual pin V0 on Blynk
     Serial.print("flame:");
     Serial.println(data);  // Print flame status on Serial Monitor
     if (data == 0) {
       Blynk.logEvent("flame_alert");  // log flame alert event if sensor detects flame
     }
   }
   

Reference

• Blynk Documentation

• Blynk Quickstart

• Blynk.virtualWrite()

• Blynk.logEvent()

• Why we use Blynk timer?