RFID Reader ID12-LA reads every card as ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

Question

My new RFID reader ID12-LA by SparkFun can recognise an RFID tag, but it can't read its tag number - the Arduino IDE outputs the tag as ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

Any help on how to convert this into a proper ID would be much appreciated - btw I have tried other baud rates; no difference.

Thanks, Raihaan

Edit - the code I'm using is this:

#include <SoftwareSerial.h>

SoftwareSerial rSerial(4,5);

void setup() {
    rSerial.begin(9600);
}

void loop() {
    if (rSerial.available() > 0) {
        int b = rSerial.read();
        Serial.print(b);
        Serial.print(" ");
    }
}

This now returns 255 6 times... Any ideas?

Schematic:

Answer 1

If you have one of the regular Arduino models, the hardware UART is connected to pins 0 and 1, which are also used by the USB programmer and in your case obviously your serial monitor, on which you expect to see some output.

Configuring a SoftwareSerial on pins 0 and 1 is probably not going to work at all. If you need the USB programmer to stay connected and the serial monitor for debugging, you have to use different I/O pins and setup your SoftwareSerial accordingly.

I assume that you are aware that the ID12-LA chip only works on the 125 kHz band and is incompatible with common tags running on 13.56 MHz?

Answer 2

You created a SoftwareSerial connection to read from the module and then you're printing what you just read to the same module. You probably want to print to the serial monitor on your PC. You should add Serial.begin(9600); to your setup() and ensure that all print()s are to Serial and not rSerial().