Need some suggestions about antenna MiFare RC522 13.56 MHz

Thread Starter


Joined Aug 5, 2016
Hello everybody, how are you doing?

I'm developing a custom Arduino UNO board that includes a MIFARE RC522 chip. The communications between the ATMEGA328 and the RC522 seems to be working since the serial console is showing this:

Looking for MFRC522.
Found chip RC522 Firmware version: 0x92

But I'm not able to read any tag. I have a RC522 shield for testing and with it I can read all my tags.

I made some mistakes in the design of the PCB antenna. At the beginning I was having a gain of 230mV and 13.56 MHz, so my first impressions were that the strength of the signal was the problem, I made some cuts to the board and now the oscilloscope shows about 10.7V and 13.56 MHz (Wave.jpg). I don't have the expertise to know what is wrong with my design. I attached the eagle project. It's a little frustrating because my first attempt was using a PIC16@3.3v (white board of the Boards.jpg) and the board works but now with Arduino@5V with a shifter I have communication with the chip but I'm not able to read anything.

I uploaded the Eagle files with the original design (v3) and the modified (v4, not yet tested)

This is the sample code and tutorial I'm using

Any suggestion is appreciated

Thanks and best regards.
Wave.jpg Boards.jpg