NFC developed from contactless radio frequency identification (RFID) and was jointly developed by Philips semiconductor (now NXP semiconductor), Nokia and Sony.

Its foundation is RFID and Internet technology.

NFC works at 13.56MHz, the maximum transmission speed is only 424kbit/s, and the distance of effective data transmission rate is only about 10cm (in fact, the NFC distance between bus card and mobile phone is usually less than 5cm), but its advantage is that it can directly read and exchange data without troublesome pairing process. This can be understood as an interconnection technology, which can "exchange" transmission distance to achieve power consumption and security.

In addition, NFC has excellent pairing speed, less than 0.1ms (which can improve experience and security).

In contrast, Bluetooth takes about 6 seconds and infrared takes about 0.5 seconds.

NFC hardware consists of CLF (non connected front-end module), RF antenna and Se (safety element safety zone).

The clf+ antenna can be used to read the balance of ordinary bus cards, but if the mobile phone / watch is simulated as a bus card (airline card issuance and recharge), the se part needs to be added.

What we see outside is the structure of chip + coil (remove the bus card and flash bank card, which are also the two basic components inside). The coil is usually installed on the back shell or close to the battery. Usually, NFC sensing is carried out through the back of the mobile phone.

Working mode:

Point to point mode: data exchange can be carried out on two devices with NFC function, such as exchanging music, transferring files, etc.

Using this mode requires that both devices have NFC functions, and NFC file transfer is basically an abandoned transfer method.

Because NFC transmission speed is very slow, it is usually only used to transmit a single contact, website and other data and a small amount of information between mobile phones, so there are few daily use scenarios.

Card reader mode: it can be used as a contactless card reader.

It can read or write the information in the electronic tag, but because NFC tag is not widely used in the market, consumers charge the physical bus card through this mode.

However, with the gradual realization of the virtual bus card function, people will rely less on physical bus cards, and the virtual bus card service integrated into mobile phones will be more convenient.

Card emulation mode: in fact, it is equivalent to an IC card using RFID technology.

Mobile phones with NFC function can be used to replace a large number of physical IC cards (bus cards, credit cards, etc.) to realize mobile payment function.