Arduino NFC门解锁

Question

我正在尝试使用带有 NFC 扩展板的 arduino 板来解锁我的车门。

开发板:Arduino UNO Rev 3NFC 扩展板:Seeed Studio v2.0b

因此，当 NFC 标签存在时，信号会将伺服器旋转 180 度以解锁门。目前的问题是我只希望一个 NFC 标签能够解锁/锁定门，而不是任意一个。

目前任何 NFC 标签都可以转动 Helm 机。

有谁知道调用哪个函数只返回 NFC 标签的 UID，然后可以将其与已知的 NFC 标签进行比较。

http://www.seeedstudio.com/wiki/NFC_Shield_V2.0

#include <SPI.h>
#include "PN532_SPI.h"
#include "PN532.h"
#include "NfcAdapter.h"

String const myUID = "1B B3 C6 EF"; // replace this UID with your NFC tag's UID
int const greenLedPin = 3; // green led used for correct key notification
int const redLedPin = 4; // red led used for incorrect key notification

PN532_SPI interface(SPI, 10); // create a SPI interface for the shield with the SPI CS terminal at digital pin 10
NfcAdapter nfc = NfcAdapter(interface); // create an NFC adapter object

void setup(void) {
    Serial.begin(115200); // start serial comm
    Serial.println("NDEF Reader");
    nfc.begin(); // begin NFC comm

    // make LED pins outputs
    pinMode(greenLedPin,OUTPUT);
    pinMode(redLedPin,OUTPUT);

    // turn off the LEDs
    digitalWrite(greenLedPin,LOW);
    digitalWrite(redLedPin,LOW);
}

void loop(void) {

    Serial.println("Scanning...");
    if (nfc.tagPresent()) // check if an NFC tag is present on the antenna area
    {
        NfcTag tag = nfc.read(); // read the NFC tag
        String scannedUID = tag.getUidString(); // get the NFC tag's UID

        if( myUID.compareTo(scannedUID) == 0) // compare the NFC tag's UID with the correct tag's UID (a match exists when compareTo returns 0)
        {
          // The correct NFC tag was used
          Serial.println("Correct Key");
          // Blink the green LED and make sure the RED led is off
          digitalWrite(greenLedPin,HIGH);
          digitalWrite(redLedPin,LOW);

          delay(500);
          digitalWrite(greenLedPin,LOW);
          delay(500);
          digitalWrite(greenLedPin,HIGH);
          delay(500);
          digitalWrite(greenLedPin,LOW);
          // put your here to trigger the unlocking mechanism (e.g. motor, transducer)
        }else{
          // an incorrect NFC tag was used
          Serial.println("Incorrect key");
          // blink the red LED and make sure the green LED is off
          digitalWrite(greenLedPin,LOW);
          digitalWrite(redLedPin,HIGH);

          delay(500);
          digitalWrite(redLedPin,LOW);
          delay(500);
          digitalWrite(redLedPin,HIGH);
          delay(500);
          digitalWrite(redLedPin,LOW);
          // DO NOT UNLOCK! an incorrect NFC tag was used. 
          // put your code here to trigger an alarm (e.g. buzzard, speaker) or do something else
        }
    }
    delay(2000);
}

此代码有效。

Answer 1

您表明您当前正在检测到任何标签后解锁。因此您必须已经正在轮询标签。如果您使用的是原始 seeedstudio 库，则可以使用 inListPassiveTarget() 方法或(如 commesan 所示)readPassiveTargetID() 对任何被动目标执行轮询> 方法。

虽然 inListPassiveTarget() 仅返回一个 bool 值，指示是否存在任何目标，但 readPassiveTargetID() 方法为您提供了一组配置参数，还允许您检索防冲突标识符(例如 ISO 14443 A 类的 UID):

bool PN532::readPassiveTargetID(uint8_t cardbaudrate, uint8_t *uid, uint8_t *uidLength, uint16_t timeout);

你可以使用这样的方法:

uint8_t uid[16] = { 0 };
uint8_t uidLen = 0;

if (nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, &uid[0], &uidLen)) {
    // uid will now contain uidLen bytes of the anti-collision identifier
}

如果您想轮询 ISO 14443 Type A 以外的其他卡，可以使用以下定义代替 PN532_MIFARE_ISO14443A:

// ISO 14443 Type B
#define PN532_BAUD_ISO14443B   (0x03)
// FeliCa 212 kbps
#define PN532_BAUD_FELICA212   (0x01)
// FeliCa 424 kbps
#define PN532_BAUD_FELICA424   (0x02)
// Jewel Tag (NFC Forum Type 1)
#define PN532_BAUD_JEWEL       (0x04)

最后，我关于使用标签的 UID 进行访问控制的通常注意事项:不要这样做!在许多现有系统中，这已被证明是一个非常糟糕的主意。请参阅这些帖子以获取更多信息:

• Serials on NFC Tags - truly unique? cloneable?
• How to prevent NFC tag cloning?
• NFC Tag as authentication tool