Multiple readers

It is possible to use multiple readers connected to the same Arduino.

The pins MOSI, MISO and SCK can be reused:

The pins RST and SDA need to be unique for each reader.

#define SS_PIN 9
#define SS_PIN2 10
#define RST_PIN 7
#define RST_PIN2 8

MFRC522 mfrc522(SS_PIN, RST_PIN);     // Create First MFRC522 instance.
MFRC522 mfrc522_2(SS_PIN2, RST_PIN2); // Create Second MFRC522 instance.

Both instances will need to be initialised:

mfrc522.PCD_Init();    // Init First MFRC522 card
mfrc522_2.PCD_Init();  // Init Second MFRC522 card

Check two_readers example for more details.