Assignment 4

// the setup function runs once when you press reset or power the board

#include 

const int buttonPin = 26;
const int ledPin = 27;

bool buttonState = false;                                         

void setup() {
  // the setup function runs once when you press reset or power the board

Serial.begin(9600); // Initialize serial communication
pinMode(ledPin, OUTPUT); // Set LED pin as output
pinMode(buttonPin, INPUT_PULLUP); // Set button pin as input with internal pull-up resistor

}

void loop() {
// the loop function runs over and over again forever

  bool currentButtonState = digitalRead(buttonPin) == LOW; // Button pressed when LOW

  if (currentButtonState != buttonState) {  // Button has either been pressed or released since the last check
    if (currentButtonState) {  // If currentButtonState is true (button pressed):
      digitalWrite(ledPin, HIGH); // The LED is turned ON by setting it HIGH
      Serial.println("Button pressed");  // A message "Button pressed" is sent to the serial monitor
    } else {   // If currentButtonState is false (button released):
      digitalWrite(ledPin, LOW); // The LED is turned OFF by setting it LOW
      Serial.println("Button released"); // A message "Button released" is sent to the serial monitor
    }
    buttonState = currentButtonState; // Update button state
  }

  delay(50); // Short delay for button debounce
}

    
    

    const int buttonPin = 26; 
    const int ledPin = 27;     

    bool ledBlinking = false;   // Flag to track LED blinking state
    unsigned long lastPressTime = 0;  // Timestamp of the last button press
    unsigned long debounceDelay = 50; // Debounce delay in milliseconds

    void setup() {
      // the setup function runs once when you press reset or power the board

      pinMode(ledPin, OUTPUT);  // Set LED pin as output
      pinMode(buttonPin, INPUT_PULLUP); // Set button pin as input with internal pull-up resistor
    }

    void loop() {
      // the loop function runs over and over again forever

      static bool lastButtonState = HIGH; // Previous button state
      bool currentButtonState = digitalRead(buttonPin); // Current button state
    
      // Check for button press with debounce, was previously not pressed, and is now pressed
      if (lastButtonState == HIGH && currentButtonState == LOW && (millis() - lastPressTime) > debounceDelay) { // Ensure debounceDelay time has passed since the last press
        lastPressTime = millis(); // Update lastPressTime to the current time (from millis())
        ledBlinking = !ledBlinking; // Toggle LED blinking state
      }
      lastButtonState = currentButtonState; //Update lastButtonState to the current state for the next loop iteration
    
      if (ledBlinking) { //If the LED is in blinking mode
        // Blink LED twice with a 0.5s delay
        for (int i = 0; i < 2; i++) { // A loop to blink the LED twice.
          digitalWrite(ledPin, HIGH); //Turn ON LED for 0.5 s
          delay(500);
          digitalWrite(ledPin, LOW); //Turn Off LED for 0.5 s
          delay(500);
        }
        ledBlinking = false; // Reset after blinking
      } else { //  If ledBlinking is false, the LED remains off
        digitalWrite(ledPin, LOW); // LED is off when not blinking
      }
    }
  

    #include 

      const int buttonPin = 26;
      const int ledPin = 27;
      const int tempSensorPin = 35;  
      
      // Parameters for the Voltage Divider
      const float Vref = 3.3;  // ESP32 ADC reference voltage
      const int ADC_Max = 4095;  // 12-bit ADC resolution
      const int R_fixed = 10000; // Fixed resistor value (10kΩ)
      
      bool buttonState = false; // Variable to hold the button state
      
      void setup() {
        // Initialize serial communication
        Serial.begin(9600);
        pinMode(ledPin, OUTPUT); // Set LED pin as output
        pinMode(buttonPin, INPUT_PULLUP); // Set button pin as input with internal pull-up resistor
      }
      
      void loop() {
        bool currentButtonState = digitalRead(buttonPin) == HIGH; // Button pressed when HIGH
      
        if (currentButtonState != buttonState) {
          if (currentButtonState) {
            digitalWrite(ledPin, HIGH); // Turn LED on
            Serial.println("Button pressed");
          } else {
            digitalWrite(ledPin, LOW);  // Turn LED off
            Serial.println("Button released");
          }
          buttonState = currentButtonState; // Update button state
        }
      
   // Read temperature sensor value (analog voltage) from the temperature sensor and store it in tempValue
  int tempValue = analogRead(tempSensorPin); 

  // Avoid division by zero by checking if Vout is close to Vref
  if (tempValue == 0 || tempValue == ADC_Max) { // If tempValue is 0 or equals ADC_Max (typically 1023 for a 10-bit ADC)
    Serial.println("Invalid sensor reading."); //  If an invalid reading is detected, it prints "Invalid sensor reading"
  } else {
    // Convert analog value to voltage
    float Vout = tempValue * (Vref / ADC_Max); //Vout is computed by scaling tempValue to the reference voltage (Vref)

    // Calculate the NTC resistance using the Voltage Divider formula
    float R_NTC = (R_fixed * (Vref - Vout)) / Vout;

    // Calculate Temperature using the Beta parameter equation
    float Beta = 3950.0; // Beta parameter for the NTC thermistor
    float T0 = 298.15; // Reference temperature (25°C in Kelvin)
    float R0 = 10000.0; // NTC resistance at 25°C (10kΩ)
    float temperatureK = (Beta * T0) / (Beta + (T0 * log(R_NTC / R0))); // Beta Parameter eauatioq
    float temperatureC = temperatureK - 273.15; Converting to Celsius

    // Print the temperature in Celsius to Serial Monitor 
    Serial.print("Temperature: ");
    Serial.print(temperatureC);
    Serial.println(" °C");
  }

  delay(1000); // Delay 1 s before next reading
}
  

    #include 
      #include 
      #include 
      
      // LCD I2C address and dimensions
      LiquidCrystal_I2C lcd(0x27, 16, 2);
      
      // Pin definitions
      const int tempSensorPin = 33; 
      const int buttonPin = 12;     
      const int ledPin = 14;        
      
      // Constants for temperature calculation
      const float Vref = 3.3;       // Reference voltage
      const int ADC_Max = 4095;     // Maximum ADC value for ESP32 (12-bit ADC)
      const float R_fixed = 10000;  // Fixed resistor value in ohms
      const float Beta = 3950.0;    // Beta parameter for the NTC thermistor
      const float T0_ref = 298.15; // Reference temperature (25°C in Kelvin)
      const float R0 = 10000.0;     // NTC resistance at 25°C (10kΩ)
      
      void setup() {
        // Initialize serial communication
        Serial.begin(115200);
      
        // Initialize the LCD
        lcd.init();
        lcd.backlight();
      
        // Initialize the button pin
        pinMode(buttonPin, INPUT_PULLUP);
      
        // Initialize the LED pin
        pinMode(ledPin, OUTPUT);
      }
      
      void loop() {
        // Read temperature sensor value
        int tempValue = analogRead(tempSensorPin);
      
        // Avoid division by zero by checking if Vout is close to Vref
        if (tempValue == 0 || tempValue == ADC_Max) {
          Serial.println("Invalid sensor reading.");
        } else {
          // Convert analog value to voltage
          float Vout = tempValue * (Vref / ADC_Max);
      
          // Calculate the NTC resistance using the Voltage Divider formula
          float R_NTC = (R_fixed * (Vref - Vout)) / Vout;
      
          // Calculate Temperature using the Beta parameter equation
          float temperatureK = (Beta * T0_ref) / (Beta + (T0_ref * log(R_NTC / R0)));
          float temperatureC = temperatureK - 273.15; // Convert to Celsius
      
          // Print the temperature to Serial Monitor
          Serial.print("Temperature: ");
          Serial.print(temperatureC);
          Serial.println(" °C");
      
          // Display appropriate message based on temperature on LCD
          lcd.clear();
          if (temperatureC < 15) {
            lcd.print("Cold");
          } else if (temperatureC >= 15 && temperatureC <= 25) {
            lcd.print("Normal");
          } else {
            lcd.print("Hot");
          }
      
          // Display the temperature on the second line of the LCD
          lcd.setCursor(0, 1);
          lcd.print(temperatureC);
          lcd.print(" C");
        }
      
        delay(1000); // Delay 1 second before next reading
      }