RFID-Based Smart Servo Lock System using Arduino UNO R4 Wi-Fi

1// RFID-triggered servo: initial 150deg -> on scan move to 0deg, hold 5s, return to 150deg
2// Requires MFRC522 (Miguel Balboa) and Servo libraries
3// Servo signal on pin D6. RC522 wiring per comments below.
4
5#include <SPI.h>
6#include <MFRC522.h>
7#include <Servo.h>
8
9#define RST_PIN    9    // RC522 RST
10#define SS_PIN     10   // RC522 SDA/SS
11#define SERVO_PIN  6    // servo signal pin
12
13// Authorized UID bytes (your card)
14const byte AUTH_UID[4] = { 0x2A, 0x7E, 0x17, 0xB1 };
15
16MFRC522 mfrc522(SS_PIN, RST_PIN);
17Servo myServo;
18
19const int initialPos = 150;              // starting position (deg)
20const int triggeredPos = 0;              // position to move to when RFID read (deg)
21const unsigned long holdTimeMs = 5000UL; // hold time at triggeredPos (ms)
22const int stepDelay = 8;                 // ms delay between degree steps for smooth movement
23
24void setup() {
25  Serial.begin(115200);
26  while (!Serial) { } // wait for Serial on some boards (harmless on others)
27
28  SPI.begin();
29  mfrc522.PCD_Init();
30
31  myServo.attach(SERVO_PIN);
32  myServo.write(initialPos); // place servo at initial position
33  Serial.println();
34  Serial.println("RFID -> Servo ready.");
35  Serial.print("Initial angle: ");
36  Serial.print(initialPos);
37  Serial.println(" deg");
38  Serial.println("Scan authorized card to trigger movement.");
39}
40
41void loop() {
42  // look for a new card
43  if (!mfrc522.PICC_IsNewCardPresent()) {
44    return;
45  }
46  if (!mfrc522.PICC_ReadCardSerial()) {
47    return;
48  }
49
50  // Print scanned UID
51  Serial.print("Scanned UID: ");
52  for (byte i = 0; i < mfrc522.uid.size; i++) {
53    if (mfrc522.uid.uidByte[i] < 0x10) Serial.print("0");
54    Serial.print(mfrc522.uid.uidByte[i], HEX);
55    if (i < mfrc522.uid.size - 1) Serial.print(":");
56  }
57  Serial.println();
58
59  // Only react if UID size is 4 and matches AUTH_UID
60  if (mfrc522.uid.size == 4) {
61    bool match = true;
62    for (byte i = 0; i < 4; i++) {
63      if (mfrc522.uid.uidByte[i] != AUTH_UID[i]) {
64        match = false;
65        break;
66      }
67    }
68
69    if (match) {
70      Serial.println("Authorized card detected. Moving servo 150 -> 0, hold 5s, return to 150.");
71      moveServoSmooth(initialPos, triggeredPos, stepDelay);
72      delay(holdTimeMs);
73      moveServoSmooth(triggeredPos, initialPos, stepDelay);
74      Serial.println("Movement complete. Waiting for card removal before next trigger.");
75
76      // Halt card & stop crypto
77      mfrc522.PICC_HaltA();
78      mfrc522.PCD_StopCrypto1();
79
80      // Wait until the card is removed to avoid immediate retrigger
81      while (mfrc522.PICC_IsNewCardPresent() || mfrc522.PICC_ReadCardSerial()) {
82        delay(100);
83        // clear any repeated read
84        if (mfrc522.PICC_IsNewCardPresent()) {
85          mfrc522.PICC_HaltA();
86          mfrc522.PCD_StopCrypto1();
87        }
88      }
89      Serial.println("Card removed. Ready.");
90    } else {
91      Serial.println("UID NOT authorized. Ignored.");
92    }
93  } else {
94    Serial.println("UID length not 4 bytes — ignored.");
95  }
96
97  // final cleanup and small debounce
98  mfrc522.PICC_HaltA();
99  mfrc522.PCD_StopCrypto1();
100  delay(150);
101}
102
103// Smooth servo movement helper: moves degree-by-degree and prints each angle to Serial
104void moveServoSmooth(int fromDeg, int toDeg, int stepDelayMs) {
105  if (fromDeg == toDeg) {
106    myServo.write(fromDeg);
107    Serial.print("Angle: ");
108    Serial.print(fromDeg);
109    Serial.println(" deg");
110    return;
111  }
112
113  int step = (toDeg > fromDeg) ? 1 : -1;
114  for (int deg = fromDeg; deg != toDeg; deg += step) {
115    myServo.write(deg);
116    Serial.print("Angle: ");
117    Serial.print(deg);
118    Serial.println(" deg");
119    delay(stepDelayMs);
120  }
121  // final position
122  myServo.write(toDeg);
123  Serial.print("Angle: ");
124  Serial.print(toDeg);
125  Serial.println(" deg");
126}