IoT Smoke Alarm

EMBEDDED SYSTEMS

I wanted to make a smoke alarm that informs all the members of a household when it's triggered by sending a notification to their smartphones using PushBullet as the Cloud Notification system.

This project was done in 2019.

VIEW CODE ON GIT

The main problem of the project was the Carbon Monoxide Sensor itself. The MQ-7 Sensor is also affected by both moisture and temperature, as a result, the data logger would have to take into account both factors.

One possible improvement other than not using the Arduino IDE was adding a low pass filter in series with the analog input so that results would be more consistent.

			// LED Display Libs
#include "SPI.h"
#include "Wire.h"
#include "stdio.h" 
#include "Adafruit_GFX.h"
#include "Fonts/FreeSans9pt7b.h"
#include "Adafruit_SSD1306.h"
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
#define OLED_ADDER 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT);

// Gas Sensor & LED Alert Pins
#define gasSensor 34
#define alertLED 23
#define button 32
#define test 33
int alertValue = 0;
 
// Wifi and IoT Libs and Values
// * Hidden for security reasons
#include "WiFi.h"
#include "WiFiClientSecure.h"
#define WIFI_SSID "NETGEAR50" 
#define WIFI_PASS "aquaticpanda498"
#define API_KEY "dkmxnPR2PPNL6Spb1sNZxP"
#define SERVER "maker.ifttt.com"
#define PORT 443


void setup() {
  int i = 10; 
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDER);
  pinMode(alertLED, OUTPUT);
  pinMode(button, INPUT_PULLUP);
  // Starts the Wifi
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  // If the Wifi cannot connect to the modem
  while(WiFi.status() != WL_CONNECTED && i >=0) {
    delay(1000);
    Serial.print(i);
    Serial.print(", ");
    i--;
  }
}

void loop() {
 
  int gasLevel = analogRead(gasSensor); // Reads sensor value
  gasLevel = gasLevel - 1600;
  Serial.println(gasLevel);
  // Displays on I2C LED Display
  display.clearDisplay(); // Has to clear the display 
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setFont(&FreeSans9pt7b);
  display.setCursor(20,12);
  display.println("CO Level: ");
  display.setTextSize(2);
  display.setFont(&FreeSans9pt7b);
  display.setTextColor(WHITE);
  display.setCursor(30,45);
  display.println(gasLevel);
  display.display();
  while(alertValue == 1 && digitalRead(button) != 0){
    triggerAlarm(gasLevel);
  }
  if (digitalRead(test) == 0){ // Alert System
    alertValue = 1;
    triggerAlarm(gasLevel);
  }
  else{
    alertValue = 0;
    delay(1000);
    digitalWrite(alertLED, LOW);
  }
}

void triggerAlarm(int gasLevel){
  sendAlert(gasLevel);
  for (int x = 0;x<5;x++){
    digitalWrite(alertLED, HIGH);
    delay(100);
    digitalWrite(alertLED, LOW);
    delay(100);
  }
}

void sendAlert(int gasLevel) {
  // Creates a WiFi client
  WiFiClientSecure client; 
  if (!client.connect(SERVER, PORT)) {
    Serial.println("Connection failed");
    return;
  }
  // URL for the trigger
  String event = "smokeAlert";
  String url = "/trigger/";
  url += event;
  url += "/with/key/";
  url += API_KEY;
  url += "?value1=";
  url += String(gasLevel);
  
  Serial.print("Requesting URL: ");
  Serial.println(url);
  // Sends a request
  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
               "Host: " + SERVER + "\r\n" + 
               "Connection: close\r\n\r\n");
  // Client ends
  client.stop();
}