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

  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);

  pinMode(2, INPUT_PULLUP);
}

void loop()
{
  int current   = analogRead(A0);
  int voltage   = analogRead(A1);
  int vibration = analogRead(A2);

  bool fault = false;

  // Current Fault
  if(current > 800)
  {
    Serial.println("FAULT: OVERCURRENT");
    fault = true;
  }

  // Voltage Fault
  else if(voltage < 200)
  {
    Serial.println("FAULT: UNDERVOLTAGE");
    fault = true;
  }

  // Vibration Fault
  else if(vibration > 700)
  {
    Serial.println("FAULT: HIGH VIBRATION");
    fault = true;
  }

  else
  {
    Serial.println("SYSTEM OK");
  }

  if(fault)
  {
    digitalWrite(6,HIGH);   // Red ON
    digitalWrite(8,LOW);    // Green OFF

    tone(7,1000);           // Buzzer ON
  }
  else
  {
    digitalWrite(6,LOW);    // Red OFF
    digitalWrite(8,HIGH);   // Green ON

    noTone(7);              // Buzzer OFF
  }

  delay(500);
}