Reference the attached datasheet.
The 'T' in the CR003
T indicates the reader module interface is a TTL UART.
However, this specific reader does not have an built-in antenna, therefore you will need to furnish an appropriate external antenna.
Another common issue is ensuring the RFID tag is compatible with the RFID reader module.
The RFID tag must be 125kHz and utilize an EM4001 compatible transponder.
Not all RFID tags are created equal. :wink:
Before connecting the RFID module to the microcontroller, ensure both the antenna and RFID tag are functional by checking the output of pin 28 as per the datasheet.
One of the most straight forward ways would be to construct a similar circuit to that given in the datasheet:
If the antenna, RFID tag and RFID reader module are functioning as expected, the LED will indicate a successful read.
Once this has been determined, then concern yourself with properly interfacing the RFID reader module to the microcontroller.
BigDog