Near Field Communication (NFC) is a new technology. Devices using NFC technology (such as mobile phones) can exchange data when they are close to each other. It is developed from the integration of contactless radio frequency identification (RFID) and internet technology. By integrating the functions of sensor card reader, sensor card and point-to-point communication on one chip, the functions of mobile payment, electronic ticketing, access control and mobile identity are realized by using mobile terminals.
principle of operation
NFC is a short-range high-frequency radio technology. Ncip-1standard stipulates that the communication distance of NFC is within 10 cm, the working frequency is 13.56MHz, and the transmission speed is 106Kbit/s, 2 12Kbit/s or 424kbit/s .. nfcip. The standard also defines the transmission protocol of NFC, including startup protocol and data exchange method.
NFC working mode is divided into passive mode and active mode. In the passive mode, the NFC initiator (also called the master device) needs a power supply device, and the master device uses the energy of the power supply device to provide a radio frequency field and send data to the NFC target device (also called the slave device), and the transmission rate should be one of 106kbps, 2 12kbps or 424kbps. The slave device does not generate a radio frequency field, so it does not need a power supply device. Instead, the RF field generated by the master device can be used to convert it into electric energy, supply power to the circuit of the slave device, receive the data sent by the master device, and use the load modulation technology to transmit the slave device data back to the master device at the same speed. In this working mode, the slave device does not generate the RF field, but passively receives the RF field generated by the master device, so it is called passive mode. In this mode, the NFC master device can detect the contactless card or NFC target device and establish a connection with it.
In active mode, both the initiator and the target device must actively generate RF fields when sending data to each other, so it is called active mode, and both of them need power supply equipment to provide energy for generating RF fields. This communication mode is the standard mode of peer-to-peer network communication and can obtain very fast connection rate.