#define BATTERY_PIN A0
#define RED_LED 2
#define GREEN_LED 3
#define BUZZER 4

float voltage = 0.0;
int soc = 0;

void setup() {
  Serial.begin(9600);

  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  Serial.println("Basic Battery Management System");
}

void loop() {

  int sensorValue = analogRead(BATTERY_PIN);

  // Convert  ADC value to voltage
  voltage = (sensorValue / 1023.0) * 5.0;

  // SOC Estimation
  soc = map(voltage * 100, 320, 420, 0, 100);

  // Limit SOC range
  if (soc > 100) soc = 100;
  if (soc < 0) soc = 0;

  Serial.print("Battery Voltage: ");
  Serial.print(voltage);
  Serial.println(" V");

  Serial.print("Estimated SOC: ");
  Serial.print(soc);
  Serial.println(" %");

  // Protection Logic

  // Undervoltage
  if (voltage < 3.3) {

    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);

    tone(BUZZER, 1000);

    Serial.println("ALERT: UNDER VOLTAGE");

  }

  // Overvoltage
  else if (voltage > 4.2) {

    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, HIGH);

    tone(BUZZER, 2000);

    Serial.println("ALERT: OVER VOLTAGE");

  }

  // Normal Condition
  else {

    digitalWrite(RED_LED, LOW);
    digitalWrite(GREEN_LED, HIGH);

    noTone(BUZZER);

    Serial.println("Battery Status: NORMAL");
  }

  Serial.println("---------------------");

  delay(1000);
}