RFID Antenna tuning circuit problem - MFRC522

Thread Starter


Joined Oct 29, 2019
See attached circuit diagram of a simple MFRC522 RFID circuit,

The chip is configured to work with I2C and the controller has full access to the registers, everything seems to work except that the antenna doesn't receive and transmit (doesn't react when a tag is in range),

Note: I use basic Arduino example code to test the circuit.

Problem: The antenna tuning circuit is probably wrong,

I have used the attached excel sheet to calculate the values of the tuning circuit,

The Antenna inductance is about 3.7uH - 4uH
Resistance is close to 0.7 ohms


Is there anything wrong with the tuning circuit calculation?

Note: there might be other problems like PCB routing, but for a start, we need to make sure that the values of the tuning circuit are correctly calculated,