(1) The reading and writing terminal continuously transmits a set of electromagnetic waves of a fixed frequency, and the operating frequency of the non-contact type IC card is generally 13.56 mhz.
(2) In the contactless card, there is an LC series resonant circuit. When it enters the working area of the read/write terminal and the frequency is the same as the frequency of the read/write terminal, the LC resonant circuit will resonate under electromagnetic excitation.
(3) Resonance causes the capacitance in the card to load. At the other end of the capacitor, there is a one-way electronic pump that supplies the charge in the capacitor to another capacitor for storage. When the accumulated charge reaches 2V, the capacitor can be used as a power source to provide an operating voltage for the integrated circuit.
(4) The associated control logic circuit in the CMOS integrated circuit decodes the received signal.
(5) Judging the command sent by the read/write terminal based on the decoded information. If the information is read, the logic is controlled to read the relevant information from the memory. If the modification information is modified, the control logic starts the voltage pump to increase the 2V operating voltage to 15V, so that the contents of the memory (EEPROM) can be reprogrammed.
(6) When a capacitor discharge occurs, the transmitter circuit in the contactless card transmits data information and related information read from the memory to the read/write terminal.
(7) The read/write terminal processes the received information. The frequency bands used by RFID systems can be divided into low frequency and high frequency. The higher the operating frequency, the faster the communication between the card reader and the card, and the shorter the system's working time.