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

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int ACS712_PIN = 34;
const int BUZZER_PIN = 32;
const float ALARM_THRESHOLD = 15.0;

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("V:0.00  I:0.00A");
  pinMode(BUZZER_PIN, OUTPUT);
  analogReadResolution(12);
  
  // Send initial zero current command
  Serial.println("current=0.0");
}

void loop() {
  static unsigned long lastSweepUpdate = 0;
  static float sweepCurrent = -20.0;
  
  // Automatic sweep demonstration (comment if not needed)
  if (millis() - lastSweepUpdate > 1000) {
    lastSweepUpdate = millis();
    sweepCurrent += 1.0;
    if (sweepCurrent > 20.0) sweepCurrent = -20.0;
    Serial.print("current=");
    Serial.println(sweepCurrent, 1);
  }

  // Read sensor
  int raw = analogRead(ACS712_PIN);
  float voltage = raw * (5.0f / 4095.0f);
  float current = (voltage - 2.5f) * 8.0f; // 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 check
  if (fabs(current) > ALARM_THRESHOLD) {
    digitalWrite(BUZZER_PIN, HIGH);
    lcd.setCursor(0, 1);
    lcd.print("ALARM! >15A     ");
  } else {
    digitalWrite(BUZZER_PIN, LOW);
    lcd.setCursor(0, 1);
    lcd.print("Status: Normal  ");
  }
  
  delay(100);
}