RFID  frequency identification is a non-contact object recognition technology, it can automaticlly recognize target and get relevant data through rf signal, so there are so many interactive projects which need to use RFID to achieve object recognition. Generally speaking, one basic kit of RFID general system mainly consists of three parts:
 
Tag : composed by coupling components and chip, every tag have only electronic coding, adhere to the target object identifier
 
Reader : equipment used to read (sometimes can write) tag information, can be designed for handheld or stationary;
 
Antenna : transmit rf signal between the tag and reader.
 
At present there are so many RFID module, and there are difference from the interface of Arduino, we design these two version of RFID module which connect with Arduino through serial port, and both of these two version have exact same function and connection mode, but the antenna is different.
 
It support 3.3v and 5v and it work at 13.56Mhz.

Work Frequency : 13.56Mhz
 
Work Temperature : -20 ℃ － + 70 ℃

Size : 57 ×34× 6 （ mm ）

One version have separate reader and antenna, separately on two boards. Because this antenna is more bigger, therefore the detection distance can be as far as 10cm :

The other version have integrate reader and antenna, integrately on one boards, and the detection distance can be as far as 6cm :

The working  principle of RFID is actually not complex, once the tag into the working area of card reader, card reader can read the data of tag by magnetic field generated by the antenna.
 
According to the specific use of different scene, we can use different types of tags, different types of tags have different range :

In the process of actual using, we can firstly use the reader to read the ID of different tags, then we can use our Serial Dongle as serial port :
 

After connection, we use the serial debugging tool to open Serial Dongle corresponding Serial port, the baud rate is set to 19200, then send reading card order as HEX format : AA BB 02 20 22 (totally 5 bytes) :
 

 

If no cards within the working area of RFID module, then the RFID module return order as HEX format through serial port: AA BB 02 DF DD (five bytes) :
 

 

 

But  If there are cards within the working area of RFID module, RFID module red LED will be lighted, at the same time return order as HEX format through serial port : AA BB 06 20 5E 97 25 C7 0D (9 byte), and then  5E 97 25 C7 is the tag ID. Different tags returns different ID value, and we just distinguish different objests through different ID value.
 
 When geting the corresponding tags ID value, then we can recognize on Arduino, about the hardware connection, we still use the COM interface of Arduino sensor shield to connect RFID mdule with Arduino :
 

 
The corresponding Arduino code shown as below, the test tag ID is 5E 97 25 C7, when Arduino detected the corresponding tag, will light the LED on 13 digital I/O port of Arduino, and last for 1 second :

Test Code Start :

int val = 0;
int ledPin = 13;
int status = 0;
unsigned char searchCMD[] = {0xAA, 0xBB,0x02, 0x20, 0x22};
unsigned char searchRES[4];

void setup()
{
  Serial.begin(19200);
  pinMode(13, OUTPUT);
}

int searchCard()
{
  Serial.write(searchCMD, 5);
  delay(100);
  status = 0;
  while(true) {
    if (Serial.available() > 0) {
      val = Serial.read();
     
      switch (status) {
        case 0:  // parse 0xAA
          if (val == 0xAA) status = 1;
          break;
        case 1: // parse 0xBB
          if (val == 0xBB) status = 2;
          else return -1;
          break;
        case 2:
          if (val == 0x06) status = 3;
          else return -1;
          break;
        case 3:
          if (val == 0x20) status = 4;
          else return -1;
          break;
        case 4:
        case 5:
        case 6:
        case 7:
          searchRES[status - 4] = val;
          status ++;
          break;
        case 8:
          return 0; // read successfully
          break;
        default:
          return -1;
          break;
      }
     
    }
  }
}

void loop()
{
  if (searchCard() != -1) {
    if (searchRES[0] == 0x5E && searchRES[1] == 0x97 && searchRES[2] == 0x25 && searchRES[3] == 0xC7) {
      digitalWrite(13, HIGH);
      delay(1000);
      digitalWrite(13, LOW);
      delay(1000);
    }
  }
}


Item Include :

1、13.56MHz UART RFID Module ×1

2、Built-in antenna ×1

3、Welded Commom Connector Module  ×1
4、13.56MHz Mifare RFID Card ×2
5、13.56MHz RFID Key IC Tag - B ×2
6、13.56MHz RFID Key IC Tag - A   ×2

7、Arduino I2C/COM Cable 30cm  ×1
 


Document Download：

Click to download the UART datasheet

Click to download the SPI datasheet

Click to download the IIC datasheet

Click here to download the SDK

 

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