Eeprom only

#include <EEPROM.h>

int buttonPin = 2;   // Pin where the button is connected
int state = 0;       // 0 = unlocked, 1 = locked
int lastButtonState = LOW; // Keeps track of the previous button state
int buttonState;     // Stores the current button state

void setup() {
  pinMode(buttonPin, INPUT); // Set the button pin as input
  Serial.begin(9600);        // Initialize Serial for output

  // Step 1: Start EEPROM with a size of 1 byte
  EEPROM.begin(1);  // 1 byte is enough to store a single state (0 or 1)

  // Step 2: Read the saved state from EEPROM
  state = EEPROM.read(0); // Read the lock state from address 0

  // Step 3: Check the state and act accordingly
  if (state == 1) {
    Serial.println("Locked");
  } else {
    Serial.println("Unlocked");
  }
}

void loop() {
  // Step 4: Check the button press
  buttonState = digitalRead(buttonPin); // Read the button state (pressed or not)

  // Step 5: If the button was just pressed (state change)
  if (buttonState == HIGH && lastButtonState == LOW) {
    // Step 6: Toggle the lock/unlock state
    state = !state; // If state was 1 (locked), it becomes 0 (unlocked), and vice versa

    // Step 7: Write the new state to EEPROM
    EEPROM.write(0, state); // Write the state to address '0'

    // Step 8: Commit the changes to EEPROM
    EEPROM.commit(); // Save the state in flash memory

    // Step 9: Show the new state on the Serial Monitor
    if (state == 1) {
      Serial.println("Locked"); // Print "Locked" if it's now locked
    } else {
      Serial.println("Unlocked"); // Print "Unlocked" if it's now unlocked
    }
  }

  // Step 10: Update the last button state for the next loop
  lastButtonState = buttonState;

  // Step 11: Add a short delay to debounce (avoid multiple button readings at once)
  delay(50);
}