A, NFC description
NFC (Near Field Communication) Near Field Communication, IS a kind of short distance high frequency radio technology, run the 13.56 MHz frequency within 20 cm distance, its transmission speed 106 kbit/SEC, 212 kbit/SEC three or 424 kbit/s, the Near Field Communication has passed into the ISO/IEC IS 18092 international standards, ECMA - 340 standard and ETSI TS 102 190 standard,

NFC (near field communication technology is a non-contact radio frequency identification (RFID) and integrated evolved, interconnection technology, combining induction card reader, on a single chip inductor CARDS and point to point function, can in the identification and data exchange with compatible devices over short distances, the working frequency of 13.56 MHz. But the user must use the mobile payment solutions to replace special mobile phone, at present this technique is widely used in Japan and South Korea, mobile phone users with configuration pay phones can traveled across the country: their mobile phone can be used as the airport boarding validation, tower, the entrance guard key transportation IC card, credit card, payment card, etc.,

Second, the PN532 overview
PN532 is a highly integrated chip contactless, speaking, reading and writing. It consists of 80 c51 microcontroller core, integrated with 13.56 MHz of active/passive contactless communication methods and protocols,
PN532 transmission module supports six different work modes:
Read/write mode, support mechanism of ISO/IEC 14443 a/MIFARE
Read/write mode, support to get its FeliCa mechanism
Read/write mode, support mechanism of ISO/IEC 14443 b
Card operation mode, and support mechanism of ISO 14443 a/MIFARE
Operation mode and get its FeliCa mechanism
ISO/IEC18092, ECM340 point-to-point

Support the host interface:
- SPI interface
- the I2C interface
- serial UART