// Slave Arduino (simulating ESP32 at rack)
#define LED 2
#define BUTTON 3

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(BUTTON, INPUT);
  Serial.begin(9600);
}

void loop() {
  // Check for command from Master
  if (Serial.available()) {
    String cmd = Serial.readStringUntil('\n');
    if (cmd == "P1") {
      digitalWrite(LED, HIGH); // Light ON for picking
    }
  }

  // Check if button pressed (pick confirmed)
  if (digitalRead(BUTTON) == HIGH) {
    Serial.println("P1_DONE"); // Send confirmation
    digitalWrite(LED, LOW);    // Turn OFF light
    delay(500);                // Debounce
  }
}