At present, there are two kinds of IC cards: contact IC cards and contactless IC cards.
Contact type IC card obtains energy and exchange data from reader through mechanical contact; contactless IC card obtains energy and exchange data from reader writer through coil RF induction, so it is also called RF card. At present, contact IC card is common in the society. It has a large storage capacity (in megabytes), strong security function (with multiple password settings and authentication functions), and can achieve multi-purpose card. However, the reading and writing operation speed of this kind of card is slow, and the operation is not convenient. Each time the card is read and written, the card must be correctly inserted into the slot of the reader writer to complete the data exchange. In this way, it is very inconvenient to read and write the card frequently in the bus, attendance and other occasions. Moreover, the contact points of the reader and the IC card on the card are exposed, which is easy to be damaged and dirty, resulting in poor contact.
Contactless IC card is produced according to the principle of RF electromagnetic induction. Its reading and writing operations only need to put the card near the reader within a certain distance, can achieve data exchange, without any contact, use is very convenient, fast, not easy to damage. Therefore, it has a wide application prospect in public transportation, access control, campus, enterprises and other personnel management, entertainment places and so on. At present, there are mainly Mifare from Philips and temic from ATMEL.
The core of contactless IC card reader and writer is RFID technology. The reader mainly uses a special read-write processing chip MMM micro module for Mifare card. It is the core device of a small Mifare read / write device with a maximum operating distance of 20-30mm. Its functions include modulation, demodulation, RF signal generation, security management and anti-collision mechanism. The internal structure is divided into radio frequency area and interface area: the radio frequency area contains modem and power supply circuit, which is directly connected with the antenna; the interface area has a port connected with the single chip microcomputer, a transceiver connected with the radio frequency area, a 16 byte data buffer, a ROM for storing 64 pairs of transmission keys, a write only memory for storing three sets of keys, and a password for three verifications and data encryption Anti collision module and control unit for anti-collision processing. This is the core module of wireless communication with RF card, and also the key interface chip for reader to read and write Mifare card. When the reader works, it continuously sends out a set of fixed frequency electromagnetic waves (13.6mhz). When a card is close to the card, there is a LG series resonant circuit in the card, whose frequency is the same as the transmission frequency of the reader. Under the excitation of electromagnetic wave, the LG resonant circuit will resonate, so that the capacitor will be charged. At the other end of this capacitor, a unidirectional conductive electronic pump is connected to store the charge in the capacitor to another capacitor. When the capacitor is charged to 2V, the capacitor will be used as power supply to provide working voltage for other circuits on the card, transmit the data in the card or receive the data from the reader and save it.
Contact type IC card obtains energy and exchange data from reader through mechanical contact; contactless IC card obtains energy and exchange data from reader writer through coil RF induction, so it is also called RF card. At present, contact IC card is common in the society. It has a large storage capacity (in megabytes), strong security function (with multiple password settings and authentication functions), and can achieve multi-purpose card. However, the reading and writing operation speed of this kind of card is slow, and the operation is not convenient. Each time the card is read and written, the card must be correctly inserted into the slot of the reader writer to complete the data exchange. In this way, it is very inconvenient to read and write the card frequently in the bus, attendance and other occasions. Moreover, the contact points of the reader and the IC card on the card are exposed, which is easy to be damaged and dirty, resulting in poor contact.
Contactless IC card is produced according to the principle of RF electromagnetic induction. Its reading and writing operations only need to put the card near the reader within a certain distance, can achieve data exchange, without any contact, use is very convenient, fast, not easy to damage. Therefore, it has a wide application prospect in public transportation, access control, campus, enterprises and other personnel management, entertainment places and so on. At present, there are mainly Mifare from Philips and temic from ATMEL.
The core of contactless IC card reader and writer is RFID technology. The reader mainly uses a special read-write processing chip MMM micro module for Mifare card. It is the core device of a small Mifare read / write device with a maximum operating distance of 20-30mm. Its functions include modulation, demodulation, RF signal generation, security management and anti-collision mechanism. The internal structure is divided into radio frequency area and interface area: the radio frequency area contains modem and power supply circuit, which is directly connected with the antenna; the interface area has a port connected with the single chip microcomputer, a transceiver connected with the radio frequency area, a 16 byte data buffer, a ROM for storing 64 pairs of transmission keys, a write only memory for storing three sets of keys, and a password for three verifications and data encryption Anti collision module and control unit for anti-collision processing. This is the core module of wireless communication with RF card, and also the key interface chip for reader to read and write Mifare card. When the reader works, it continuously sends out a set of fixed frequency electromagnetic waves (13.6mhz). When a card is close to the card, there is a LG series resonant circuit in the card, whose frequency is the same as the transmission frequency of the reader. Under the excitation of electromagnetic wave, the LG resonant circuit will resonate, so that the capacitor will be charged. At the other end of this capacitor, a unidirectional conductive electronic pump is connected to store the charge in the capacitor to another capacitor. When the capacitor is charged to 2V, the capacitor will be used as power supply to provide working voltage for other circuits on the card, transmit the data in the card or receive the data from the reader and save it.