30. MFRC522 RFID Access Log (VMA202)

#include <SPI.h>
#include <MFRC522.h>
#include <SD.h>
#include <Wire.h>
#include <RTClib.h>

const byte sdCsPin = 10;      // VMA202 SD chip select
const byte rfidSsPin = 7;     // MFRC522 SDA/SS (not D10)
const byte rfidRstPin = 9;
const byte greenLed = 3;
const byte redLed = 4;
const byte solenoidPin = 5;
const byte buzzerPin = 6;

MFRC522 rfid(rfidSsPin, rfidRstPin);
RTC_DS1307 rtc;

// Replace these UIDs with cards scanned from Serial during setup/testing.
byte allowedUid1[] = {0xDE, 0xAD, 0xBE, 0xEF};
byte allowedUid2[] = {0x01, 0x23, 0x45, 0x67};

unsigned long unlockUntil = 0;
unsigned long denyUntil = 0;
unsigned long nextBeepAt = 0;
byte beepsLeft = 0;

bool uidMatches(byte *uid, byte *allowed, byte length) {
  for (byte i = 0; i < length; i++) {
    if (uid[i] != allowed[i]) return false;
  }
  return true;
}

bool isAllowed(byte *uid, byte length) {
  if (length == 4 && uidMatches(uid, allowedUid1, 4)) return true;
  if (length == 4 && uidMatches(uid, allowedUid2, 4)) return true;
  return false;
}

void uidToText(byte *uid, byte length, char *out, byte outSize) {
  byte pos = 0;
  out[0] = 0;
  for (byte i = 0; i < length; i++) {
    if ((pos + 3) >= outSize) break;
    sprintf(&out[pos], "%02X", uid[i]);
    pos += 2;
    if (i + 1 < length && (pos + 1) < outSize) {
      out[pos++] = ':';
      out[pos] = 0;
    }
  }
}

void logEvent(const char *uidText, bool allowed) {
  DateTime now = rtc.now();
  File logFile = SD.open("ACCESS.LOG", FILE_WRITE);
  if (!logFile) {
    Serial.println("SD log open failed");
    return;
  }
  char stamp[20];
  snprintf(stamp, sizeof(stamp), "%04d-%02d-%02d %02d:%02d:%02d",
           now.year(), now.month(), now.day(),
           now.hour(), now.minute(), now.second());
  logFile.print(stamp);
  logFile.print(",");
  logFile.print(uidText);
  logFile.print(",");
  logFile.println(allowed ? "ALLOW" : "DENY");
  logFile.close();
}

void startAllow() {
  digitalWrite(redLed, LOW);
  digitalWrite(greenLed, HIGH);
  digitalWrite(solenoidPin, HIGH);
  noTone(buzzerPin);
  unlockUntil = millis() + 3000;
  denyUntil = 0;
  beepsLeft = 0;
}

void startDeny() {
  digitalWrite(greenLed, LOW);
  digitalWrite(solenoidPin, LOW);
  digitalWrite(redLed, HIGH);
  denyUntil = millis() + 900;
  beepsLeft = 3;
  nextBeepAt = millis();
  unlockUntil = 0;
}

void serviceOutputs() {
  unsigned long now = millis();

  if (unlockUntil != 0 && now >= unlockUntil) {
    digitalWrite(solenoidPin, LOW);
    digitalWrite(greenLed, LOW);
    unlockUntil = 0;
  }

  if (beepsLeft > 0 && now >= nextBeepAt) {
    tone(buzzerPin, 1800, 80);
    beepsLeft--;
    nextBeepAt = now + 180;
  }

  if (denyUntil != 0 && now >= denyUntil) {
    digitalWrite(redLed, LOW);
    noTone(buzzerPin);
    denyUntil = 0;
  }
}

void setup() {
  pinMode(greenLed, OUTPUT);
  pinMode(redLed, OUTPUT);
  pinMode(solenoidPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  digitalWrite(solenoidPin, LOW);

  Serial.begin(9600);
  SPI.begin();
  rfid.PCD_Init();
  Wire.begin();

  if (!rtc.begin()) {
    Serial.println("RTC missing on VMA202");
  }
  if (!rtc.isrunning()) {
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }

  if (!SD.begin(sdCsPin)) {
    Serial.println("VMA202 SD init failed (CS=D10)");
  } else {
    Serial.println("VMA202 SD ready");
  }
  Serial.println("Scan a card to learn its UID, then update allowedUid arrays.");
}

void loop() {
  serviceOutputs();

  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
    return;
  }

  char uidText[24];
  uidToText(rfid.uid.uidByte, rfid.uid.size, uidText, sizeof(uidText));
  Serial.print("UID ");
  Serial.println(uidText);

  bool allowed = isAllowed(rfid.uid.uidByte, rfid.uid.size);
  logEvent(uidText, allowed);
  if (allowed) startAllow();
  else startDeny();

  rfid.PICC_HaltA();
  rfid.PCD_StopCrypto1();
}