Metal Monitor rev_04

/********* Pleasedontcode.com **********

    Pleasedontcode thanks you for automatic code generation! Enjoy your code!

    - Terms and Conditions:
    You have a non-exclusive, revocable, worldwide, royalty-free license
    for personal and commercial use. Attribution is optional; modifications
    are allowed, but you're responsible for code maintenance. We're not
    liable for any loss or damage. For full terms,
    please visit pleasedontcode.com/termsandconditions.

    - Project: Metal Monitor
    - Source Code NOT compiled for: Arduino Uno
    - Source Code created on: 2025-12-09 05:06:10

********* Pleasedontcode.com **********/

/****** SYSTEM REQUIREMENTS *****/
/****** SYSTEM REQUIREMENT 1 *****/
    /* Add additional sensors for 3 no's. so total 6 */
    /* sensors. avoid any blocking code and the system to */
    /* sense and work smoothly. */
/****** END SYSTEM REQUIREMENTS *****/


/* START CODE */

/****** DEFINITION OF LIBRARIES *****/

/****** FUNCTION PROTOTYPES *****/
void setup(void);
void loop(void);

const int sensorPin = 2;
bool lastMetalState = false;
unsigned long lastPrintTime = 0;

void setup() {
  pinMode(sensorPin, INPUT_PULLUP);  // NO PULLUP - let external circuit handle it
  Serial.begin(9600);
  Serial.println("Sensor monitor started.");
  Serial.println("If nothing prints, check wiring:");
  Serial.println("1. Sensor Brown -> +24V");
  Serial.println("2. Sensor Blue -> 24V GND");
  Serial.println("3. Sensor Black -> PC817 Anode");
  Serial.println("4. PC817 Cathode -> 24V GND");
  Serial.println("5. PC817 Output -> Arduino Pin 2");
  Serial.println("6. PC817 GND -> Arduino GND");
}

void loop() {
  int sensorValue = digitalRead(sensorPin);

  // If pin reads LOW, metal is detected (PNP+PC817 active-low)
  bool metalDetected = (sensorValue == LOW);

  // Only print when state changes
  if (metalDetected != lastMetalState) {
    if (metalDetected) {
      Serial.println("METAL DETECTED!");
    } else {
      Serial.println("Metal removed.");
    }
    lastMetalState = metalDetected;
    lastPrintTime = millis();
  }

  // If no signal for 3 seconds, warn about possible disconnection
  if (millis() - lastPrintTime > 3000) {
    Serial.println("[System idle - sensor monitoring active]");
    lastPrintTime = millis();
  }

  delay(100);  // Check 10 times per second
}

/* END CODE */