WEEK 14: INTERFACE AND APPLICATION PROGRAMMING

This week the task was to create an application that would interact with the board through Wi-Fi. I built dashboard to visualize the data from the my board.

In the way of continue with making progress on my final project, I tried to make a dashboard to visualize data from my designed PCB Board.

Group Assignment

In this group assignment, we focused on Interface and Application Programming by implementing I2C communication with the board and controlling an actuator using the Blynk app. We compared them to find the most effective solutions for our needs. This task enhanced our understanding of various tools and their applications in real-world scenarios.

Click here to open the group page

Dashboard pages developed

You can access the dashboard where it is hosted here: https://fabacademy-airquality-monitoring.onrender.com

How to access the dashboard?

To access the dashboard, it requires login. You can create an account to access the dashboard or use the already created account here: Email Address: ndayisabawilson@gmail.com , password: wilson

Database hosted on railway.app

Source code directory

All the code can be found on my github here: https://github.com/Wilsonndayisaba/fabacademy-airquality-monitoring

PROGRAMMING A DEVICE OF MY PROJECT

Main components of the device

• Seeed Studio XIAO Esp32_C3
• MQ135 Gas Sensor
• DHT22 Sensor
• LCD 20X4 With I2C

Code for the device

                 
                #include <Wire.h> 
                #include <LiquidCrystal_I2C.h> 
                #include <RTClib.h> 
                #include <DHT.h> 
                #include <WiFi.h> 
                #include <HTTPClient.h> 
                #include <ArduinoJson.h> 
                
                #define DHTPIN D2
                #define DHTTYPE DHT22
                #define MQ135_PIN A0
                #define FAN_PIN D9
                #define LAMP_PIN D10
                
                const char* ssid = "xxxxxxxxx"; // Here you have to put username of your WiFi
                const char* password = "xxxxxxxxx"; // Put Password of Your WiFi
                
                const char* serverName = "https://fabacademy-airquality-monitoring.onrender.com/sensordata";
                
                DHT dht(DHTPIN, DHTTYPE);
                RTC_DS3231 rtc;
                LiquidCrystal_I2C lcd(0x27, 20, 4); // Adjust the address if needed
                
                float Ro = 30.7;           // Initial Ro value, which will be calibrated which sensor resistor recorded
                float RL = 10.0;           // Load resistance on the board
                float cleanAirFactor = 3.6; // Sensor's Rs/Ro ratio in clean air
                
                unsigned long lastTime = 0;
                unsigned long timerDelay = 180000; // 180 seconds
                
                void setup() {
                  Serial.begin(115200);
                  lcd.init();
                  lcd.backlight();
                  dht.begin();
                
                  if (!rtc.begin()) {
                    Serial.println("Couldn't find RTC");
                    while (1);
                  }
                
                  if (rtc.lostPower()) {
                    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
                  }
                
                  Ro = calibrateMQ135(); // Calibrate MQ135 sensor
                
                  pinMode(FAN_PIN, OUTPUT);
                  pinMode(LAMP_PIN, OUTPUT);
                
                  WiFi.begin(ssid, password);
                
                  while (WiFi.status() != WL_CONNECTED) {
                    delay(1000);
                    Serial.println("Connecting to WiFi...");
                  }
                
                  Serial.println("Connected to WiFi");
                }
                
                void loop() {
                  DateTime now = rtc.now();
                
                  float sensorResistance = getResistance();
                  float ratio = sensorResistance / Ro;
                
                  // Estimate gas concentrations
                  float co2 = calculateCO2(ratio);
                  float no2 = calculateNO2(ratio);
                  float nh3 = calculateNH3(ratio);
                
                  // Read DHT22 sensor
                  float humidity = dht.readHumidity();
                  float temperature = dht.readTemperature();
                
                  // Display on LCD
                  lcd.setCursor(0, 0);
                  lcd.print("Time: ");
                  lcd.print(now.hour(), DEC);
                  lcd.print(':');
                  lcd.print(now.minute(), DEC);
                  lcd.print(':');
                  lcd.print(now.second(), DEC);
                
                  lcd.setCursor(0, 1);
                  lcd.print("Date: ");
                  lcd.print(now.year(), DEC);
                  lcd.print('/');
                  lcd.print(now.month(), DEC);
                  lcd.print('/');
                  lcd.print(now.day(), DEC);
                
                  lcd.setCursor(0, 2);
                  lcd.print("CO2: ");
                  lcd.print(co2);
                  lcd.print(" ppm");
                
                  lcd.setCursor(0, 3);
                  lcd.print("NO2: ");
                  lcd.print(no2);
                  lcd.print(" ppm");
                
                  lcd.setCursor(0, 4);
                  lcd.print("NH3: ");
                  lcd.print(nh3);
                  lcd.print(" ppm");
                
                  lcd.setCursor(0, 5);
                  lcd.print("Temp: ");
                  lcd.print(temperature);
                  lcd.print(" C");
                
                  lcd.setCursor(0, 6);
                  lcd.print("Humidity: ");
                  lcd.print(humidity);
                  lcd.print(" %");
                
                  // Control actuators based on time
                  if ((now.hour() > 18 || (now.hour() == 18 && now.minute() >= 30)) && now.hour() < 24) {
                    digitalWrite(FAN_PIN, HIGH);
                    digitalWrite(LAMP_PIN, HIGH);
                  } else {
                    digitalWrite(FAN_PIN, LOW);
                    digitalWrite(LAMP_PIN, LOW);
                  }
                
                  // Send data to server every 60 seconds
                  if (WiFi.status() == WL_CONNECTED && (millis() - lastTime) > timerDelay) {
                    HTTPClient http;
                    http.begin(serverName);
                    http.addHeader("Content-Type", "application/json");
                
                    StaticJsonDocument<200> doc;
                    doc["NO2"] = round(no2 * 100) / 100.0;
                    doc["CO2"] = round(co2 * 100) / 100.0;
                    doc["NH3"] = round(nh3 * 100) / 100.0;
                    doc["humidity"] = round(humidity * 100) / 100.0;
                    doc["temperature"] = round(temperature * 100) / 100.0;
                    doc["deviceId"] = "1";
                
                    String jsonData;
                    serializeJson(doc, jsonData);
                
                    int httpResponseCode = http.POST(jsonData);
                
                    if (httpResponseCode > 0) {
                      String response = http.getString();
                      Serial.println(httpResponseCode);
                      Serial.println(response);
                    } else {
                      Serial.print("Error on sending POST: ");
                      Serial.println(httpResponseCode);
                    }
                  
                      http.end();
                      lastTime = millis();
                    }
                  
                    delay(1000); // Update every second
                  }
                  
                  // Calculate resistance of the sensor
                  float getResistance() {
                    int sensorValue = analogRead(MQ135_PIN);
                    float voltage = sensorValue / 4095.0 * 3.3;
                    float resistance = (3.3 - voltage) * RL / voltage;
                    return resistance;
                  }
                  
                  // Calibrate the MQ135 sensor
                  float calibrateMQ135() {
                    float val = 0;
                  
                    for (int i = 0; i < 50; i++) {
                      val += getResistance();
                      delay(100);
                    }
                    val = val / 50.0;
                    return val / cleanAirFactor;
                  }
                  
                  // Placeholder functions for gas concentration calculations
                  float calculateCO2(float ratio) {
                    // Use the appropriate formula based on the MQ135 datasheet
                    return pow(10, ((-0.42 * log10(ratio)) + 1.92));
                  }
                  
                  float calculateNO2(float ratio) {
                    // Use the appropriate formula based on the MQ135 datasheet
                    return pow(10, ((-0.71 * log10(ratio)) + 0.98));
                  }
                  
                  float calculateNH3(float ratio) {
                    // Use the appropriate formula based on the MQ135 datasheet
                    return pow(10, ((-0.57 * log10(ratio)) + 1.53));
                  }               
              

The image above shows how the device is sending data in the cloud with the code shown