#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define POT_PIN 34      // Potentiometer pin
#define BUZZER_PIN 25   // Buzzer pin
#define ACS712_PIN 35   // ACS712 output pin

LiquidCrystal_I2C lcd(0x27, 16, 2);

float voltage = 100.0;  // Initial voltage
float current = 0.0;    // Current measurement
float serialCurrent = 0.0; // Current from serial input
bool useSerialCurrent = false; // Flag to use serial input

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  pinMode(BUZZER_PIN, OUTPUT);
  noTone(BUZZER_PIN);
  analogReadResolution(12);
  
  // Initialize display
  lcd.setCursor(0, 0);
  lcd.print("V:100.00 I:0.00A");
  lcd.setCursor(0, 1);
  lcd.print("SYSTEM NORMAL  ");
  
  Serial.println("System Ready");
  Serial.println("Send 'current=X.XX' to set current");
}

void loop() {
  // Handle serial commands
  if (Serial.available()) {
    String input = Serial.readStringUntil('\n');
    input.trim();
    
    if (input.startsWith("current=")) {
      serialCurrent = input.substring(8).toFloat();
      useSerialCurrent = true;
      Serial.print("Current set to: ");
      Serial.print(serialCurrent, 2);
      Serial.println("A");
    }
  }

  // Read voltage from potentiometer (80-120V range)
  int potValue = analogRead(POT_PIN);
  voltage = (potValue / 4095.0) * 40.0 + 80.0;
  
  // Get current (from serial or sensor)
  if (useSerialCurrent) {
    current = serialCurrent;
  } else {
    // Read from ACS712 simulation
    int sensorValue = analogRead(ACS712_PIN);
    float outputVoltage = sensorValue * (5.0 / 4095.0);
    current = (outputVoltage - 2.5) * 8.0; // 20A/2.5V = 8
  }
  
  // Update LCD
  lcd.setCursor(2, 0);  // Voltage
  lcd.print(voltage, 2);
  lcd.print("V ");
  
  lcd.setCursor(11, 0); // Current
  lcd.print(current, 2);
  lcd.print("A ");
  
  // Alarm system
  if (voltage < 100.0) {
    tone(BUZZER_PIN, 1000);
    lcd.setCursor(0, 1);
    lcd.print("LOW VOLTAGE!   ");
  } 
  else if (voltage > 110.0) {
    tone(BUZZER_PIN, 1500);
    lcd.setCursor(0, 1);
    lcd.print("HIGH VOLTAGE!  ");
  }
  else if (fabs(current) > 15.0) {
    tone(BUZZER_PIN, 2000);
    lcd.setCursor(0, 1);
    lcd.print("OVER CURRENT!  ");
  }
  else {
    noTone(BUZZER_PIN);
    lcd.setCursor(0, 1);
    lcd.print("SYSTEM NORMAL  ");
  }

  delay(200);
}