// Serial command pin tester for Arduino Nano
// Type a pin name (like A6 or 12) into Serial Monitor, press Enter.
// It will monitor that pin: 1 = HIGH (idle), 0 = LOW (touched to GND).

int currentPin = -1;

void setup() {
  Serial.begin(9600);
  Serial.println("Pin tester ready.");
  Serial.println("Type a pin name (e.g., A0, A6, 12) and press Enter to monitor.");
}

void loop() {
  // --- check for serial input ---
  if (Serial.available()) {
    String input = Serial.readStringUntil('\n');
    input.trim();

    if (input.length() > 0) {
      int pin = parsePin(input);
      if (pin >= 0) {
        currentPin = pin;
        pinMode(currentPin, INPUT_PULLUP);
        Serial.print("Now monitoring pin ");
        Serial.println(input);
      } else {
        Serial.print("Invalid pin: ");
        Serial.println(input);
      }
    }
  }

  // --- if a pin is selected, show its state ---
  if (currentPin >= 0) {
    int val = digitalRead(currentPin);
    Serial.print("Pin ");
    Serial.print(currentPin);
    Serial.print(" = ");
    Serial.println(val);
    delay(500);
  }
}

// --- helper: convert string like "A6" or "12" into Arduino pin number ---
int parsePin(String s) {
  s.toUpperCase();
  if (s.startsWith("A")) {
    int anum = s.substring(1).toInt();
    if (anum >= 0 && anum <= 7) {
      return A0 + anum;
    }
  } else {
    int dnum = s.toInt();
    if (dnum >= 0 && dnum <= 13) {
      return dnum;
    }
  }
  return -1; // invalid
}