Guide: RFID (RADIO FREQUENCY IDENTIFICATION) is a wireless RF identification technology that is one of automatic identification technology. Use a dedicated RFID reader and a dedicated RFID tag that can be attached to the target, and the information is transmitted from the reader by the label. Compared to traditional barcodes, magnetic cards and other automatic identification technologies, RFID technology has significant advantages in many aspects, such as environmental adaptability, working distance, confidentiality, and intelligence. In addition, it can also be identified simultaneously with a plurality of high-speed motion.
RFID technology is rapidly mature, and many countries will actively promote it as an important industry. As far as it is, China's passive ultra-high frequency development is still in the primary stage, and it is urgent to break through technology. It not only needs to improve business model more innovation. If you want to have passive super high frequency market, you must effectively solve problems. This article provides a feasible solution for the implementation of the RF communication system.
1 system overall design
This article is a C8051F310 microcontroller and FM1702SL read and write chip. The C8051F310 has a 10-bit conversion rate of ADC, high-speed 8051 microcontroller core, 29/25 port I / O, etc.; Non-contact read card FM1702SL is based on ISO14443 standard, satisfying encryption algorithm Many species, support non-contact communication protocols under 13.56 MHz Typea.
After the reader encodes the information to be transmitted, loaded on the radio frequency carrier of 13.56 MHz, transmits outwards through the antenna, and forms a stable electromagnetic field, providing energy for the RFID tag. When the RFID electronic tag enters the workspace of the reader, the card antenna receives this signal and energy, and the label is activated. The label chip determines this signal, such as valid signaling, reads the relevant information from the memory, and emits out by the interior antenna. The antenna receives this signal, the FM1702SL internal receiver detects and demodulates the signal and processes according to the setting of the register, and then sent to the host system. The host system determines whether the label is legal and processed, and the instruction to the reader is then issued.
2 system hardware design
2.1 Overall circuit design
The external power supply is 220 V alternating current, and it is stabilized by the switching power source at 5 V, and power is supplied to the board. Since the power supply voltage of the C8051F310 single-chip supply is 2.7 V ~ 3.6V, the supply voltage of the radio frequency read and write chip FM1702SL is 3 V ~ 5 V, so the voltage is stabilized in 3.3 V power supply with a AMS1117 regulator. The RS232 realizes level conversion by SP3232, connected to the C8051F310, and the C8051F310 single chip is connected to the FM1702SL through the SPI port, and thereby controlling the read and write chip. The FM1702SL is again connected to the antenna to achieve signal transmission and reception.
In summary, the system is mainly composed of a power module, a serial communication module, an MCU module, an FM1702SL interface module, and an antenna matching circuit module.
2.2 FM1702SL circuit design
FM1702SL is a highly integrated chip, and its peripheral circuit requires several decoupling capacitors and a crystal and one 0 Ω resistance. The system adopts the PCB antenna design, and the FM1702SL circuit is shown in Figure 1.
Figure 1 FM1702SL circuit
3 system software design
First initialize the C8051F310 and FM1702SL, then perform the test command for the search, if there is a card entry, determine whether the signaling is effective, if you have a conflict mechanism for valid signaling, select the card, then proceed, pass the card, write Card, stop and other operations, according to this cycle. Sub-function of some programs is as follows:
Char PCDRequest (unsigned char req_code, unsigned char * ptagtype)
// anti-rush
// INPUT: G_CSNR = storage order number (4byte) memory single-headed address
// output: status = mi_ok: success
// Get the serial number placed in the designated unit
Char pcdanticoll (unsigned char * psnr)
// Select a card
4 Conclusion
This paper uses C8051F310 and FM1702SL to realize the hardware and software design of the RF communication system, discusses the design principle of the main circuit, and introduces the design of some of the program. The design of this radiofrequency reader is actually meaningful. Radio frequency identification technology is also one of the research contents of the Internet of Things. This paper also has important guiding significance on the research on the foundation network.
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