The MFRC522 is a highly integrated reader/writer IC for contactless communication at 13.56 MHz. It supports ISO 14443A cards (MIFARE Classic, MIFARE Ultralight, NTAG) and is commonly used for access control and payment systems.
| IC | MFRC522 |
| Frequency | 13.56 MHz |
| Interface | SPI / I²C / UART |
| Supply voltage | 2.5 – 3.3 V |
| Read range | 0 – 6 cm (card dependent) |
| Supported cards | MIFARE Classic / Ultralight / NTAG |
| Standard | ISO 14443A |
| Data rate | 106 / 212 / 424 kbit/s |
The reader generates a 13.56 MHz electromagnetic field via the antenna coil. A passive transponder (card or fob) harvests energy from the field, activates its IC, and transmits its UID using load modulation. The reader detects the modulation and decodes the response.
Short range (< 6 cm). Metal surfaces attenuate the field significantly. One card at a time in collision-free mode. MIFARE Classic uses proprietary crypto (Crypto-1) which has known weaknesses. High-frequency interference from adjacent electronics.