10+ RFID on arduino

Hey guys.

I need to read a lot of RFID's, and I want to bundle as many readers as I can on a arduino

I'm using:

the generic MFR522 RFID MODULE as the reader
Arduino Mega
the library GitHub - miguelbalboa/rfid: Arduino RFID Library for MFRC522

I made a "expander" pcb toat has only some headers to stick the rfids in them.
I use a level shifter between the mega and the readers.

MISO, MOSI, SCK, RESET are all shared with the readers, only SS is different for each reader.

It works well if I put the readers in the header, but if I use some wires (5cm) between the reader and the header, it won't work anymore.

The reader is not detected anymore.

Since it works directly in the header and not with the wires, I think is something related to noise?

Any ideea how to make it work?
Lower the clock, add some filtering stuff?

Any ideea is welcomed.


Or the wires are not connected to the reader.

Do the LED on the readers light up when connected with wires?

Try using different wires of take an Multimeter to check if the wires connect well enough.


The wires are making contact.

I tried with multiple sets of wires, checked the continuity of the wires (from the reader to the arduino), and they all are connected.

It just doesn't work when it's not directly in header.

And I don't really know why.

Do I have to add some extra hardware to the lines? a pullup, capacitor, or something?