RDM6300 continuous RFID tag read

Question

I have an RDM6300 connected to an Arduino Mega and code that can read the tag just fine:

// Function prototypes
void setup(void);
void loop(void);

// RDM6300 packet details
#define RDM6300_PACKET_SIZE  14
#define RDM6300_PACKET_BEGIN 0x02
#define RDM6300_PACKET_END   0x03

// Globack for reading RFID data
char buff[RDM6300_PACKET_SIZE];
uint32_t tag_id;
uint8_t checksum;

void setup(void) {
  Serial.begin(9600);
  Serial.println("Setting up...");

  // RFID board setup
  Serial1.begin(9600);

  Serial.println("READY. Scanning tags...");
}

void loop(void) {
  while (Serial1.available() > 0) {
    if (Serial1.peek() == RDM6300_PACKET_BEGIN || Serial1.read()) {
      Serial1.readBytes(buff, RDM6300_PACKET_SIZE);
      if (buff[13] != RDM6300_PACKET_END) {
        Serial.println("Bad1");
      }
      else {
        buff[13] = 0;
        checksum = strtol(buff + 11, NULL, 16);
        buff[11] = 0;
        tag_id = strtol(buff + 3, NULL, 16);
        buff[3] = 0;
        checksum ^= strtol(buff + 1, NULL, 16);
        for (uint8_t i = 0; i < 32; i += 8) checksum ^= ((tag_id >> i) & 0xFF);
        if (checksum) {
          Serial.println("Bad2");
        }
        else {
          Serial.println(tag_id);
        }
      }
    }
    else {
      Serial.println("Bad3");
      Serial.println(Serial1.peek(), HEX);
    }
    Serial.println("END");
  }
}

However, the output stops after reading the tag around 28 times sometimes (more, sometimes less...) . If I remove the tag from the "read" area and put it back on it start reading again for a number of times and then stop.

I have an LED connect to the RDM6300 board that is supposed to show when it detects a tag and it does blink while I hold the tag over the antenna but also stops when the Arduino stops receiving data.

As the RDM6300 is supposed to be a continuous RFID reader I was expecting to receive data for the duration I kept the tag over the antenna.

Anyone faced this same thing and found a solution ?

Thanks for any hints.

Answer 1

Ok, so it seems to be related to the tags. The "standard" keychain and credit-card type cards when used with the RDM360 only emit a single time their ID.

The same tags when used with the RDM3600 module will emit their tags a few times, but at some point the antenna can not provide enough power for the tag to emit again and the flow stops.

Fortunatly the tags I use for this project are very small tags made for birds (https://eccel.co.uk/product/3-3mm-em4102-pit-bird-tag-grey/) and when used with the RDM360 will continuoisly retransmit. I guess they need less power and the antenna is able to provide enough.

If you want to use continuous reading using regular tags, I believe there is still a way... If you "reset" the RDM360 or RDM3600 it forces "re-energize" of the tag and transmission resumes. So one could use a simple transistor to switch on and off the power to the RFID module using an Arduino I/O.