Pin order, starting from the bottom left hand pin (in case your MFRC522 doesn't have pin markings like the B2CQSHOP one):
| Pins | SPI | UNO | Mega2560 | Leonardo/Due |
|---|---|---|---|---|
| 1 | SDA (SS) | 10 | 53 | 10 |
| 2 | SCK | 13 | 52 | SCK1 |
| 3 | MOSI | 11 | 51 | MOSI1 |
| 4 | MISO | 12 | 50 | MISO1 |
| 5 | IRQ | * |
* |
* |
| 6 | GND | GND | GND | GND |
| 7 | RST | 5 | ? | Reset |
| 8 | +3.3V | 3V3 | 3V3 | 3.3V |
* Not needed |
||||
1 on ICPS header |
If you are planning to use other SPI components you just have to make sure each have an exclusive SS (Slave Select) line. MISO, MOSI and SCK lines may be shared. More reference regarding SPI may be found here.