0 Introduction
Radio Frequency Identification RFID (radio frequency identifiestion) is the 1990s, the rise of a non-contact automatic identification technology, its use of radio-frequency signal space coupling of the transmission characteristics, can be identified for automatic identification of objects. No need for physical contact with the process of identification, no need for optical visual, no need to manually manage to complete the information recorded and dealt with. Use of RFID technology, can achieve the goal of the campaign, multi-target identification. At the same time, RFID can read and write, be able to carry large amounts of data, confidentiality strong, and has a fear of stains, dust, and other strong environmental adaptability. It is for these other know another way unmatched advantages, RFID technology in production, logistics, communications, transportation, medical, security and other fields have a wide range of applications and great prospects for development. In RFID systems, radio frequency identification tag reader is the collection of information will give background information processing system, key equipment, ensuring a reliable RFID system plays an important role in the work. This article will be Philips's MF RC500 chip at the core of a design to AT-MEGA162 MCU controller for the radio-frequency RFID reader. It completed its Mifare one card for all to read and write and control of the operation, and can be easily embedded into other systems (such as access charges), to become part of the user's system.
1 RFID system and the basic principles of
RFID systems in general by the electronic tag, reader, the computer component of the background. RFID, also known as radio frequency tags, transponders or vector data; reader, also known as the first time, or to read out the communication device (RFID depends on whether the data can be rewritten wireless). RFID reader and, through the coupling radio-frequency signal components to achieve the space (no contact) coupling; coupling in the channel, based on timing relations and realize the energy transmission and data exchange, and then by the computer back to the time The read-write data storage and management analysis trio R FID operation of the basic components of the system as shown in Figure I.
Figure 1 RFID system, the basic component of
Working hours system, a reader in the region emit electromagnetic wave (the size of the region depends on the frequency and antenna size), have a label inside the LC series resonant circuit, the frequency reader with the launch of the same frequency. When the RFID reader through an effective regional electromagnetic waves, electromagnetic waves in the incentive, the labels have a resonance LC resonant circuit, resulting in induction charge accumulated to a certain extent, the capacitor can be used as power for other circuits to provide voltage, The card will launch the data out or receive data reader to the card reader to receive data, decoding and error checking to determine the validity of the data, and then, through the RS-232, RS-422, RS - 485 or wirelessly transmit data back to the computer, data processing.
RFID system standardization and development of high and low efficiency of the system can be widely used in the primary factor. At present, the production of RFR〕 Most of the products using their own standards, the international community have not formed a unified standard. Now, for the use of RFID standards have several "S010536, 5014443, IS015693 and L9018000. Which is the most widely used LSO14443, by the standards of the physical characteristics of the RF power and signal interface, initialization and anti-collision Transfer Protocol, as well as four parts. Because of the Philips family of RFID chips, MF RC500 can IS014443A support of all levels to facilitate the development of the system, the use of the MF RC500 can greatly enhance the reader's efficiency in the development and the formation of a unified standard.
2 reader hardware system design
Radio-frequency RFID reader hardware, including the main microprocessor circuit AT-MEGA162, MF RC500, antenna circuit, and so on. A few of them to read and write RFID chip MF RC500 is the core of the reader, it will complete the reading and writing e-label all the necessary functions, including RF signal generation, modulation, demodulation, security certification and anti-collision, and so on. MCU microprocessor through the core of MFR C501〕 special memory read and write registers to control the MF RC500. MF RC500 is actually between the MCU tag with the electronic exchange of information of the media. Any labels are required to read and write data to pass through the MF RCS00. Send different types of instructions to the MF RC500, on the MF RC500 will be able to achieve control.
2.1 MF RC500 features introduced
MF RC5 00 advanced modulation and demodulation concept of a fully integrated in 13.56 M Hz under all types of passive non-contact and communication protocol. Its internal transmitter do not need to increase the active part of the circuit will be able to drive directly from the operation near the antenna, up to 100 mm; part of the receiver to provide a strong and effective demodulation and decoding circuitry for IS014443A compatible transponder signal; digital IS014443A part of the frame and handle error detection (and the odd-even CRC). In addition, it has a clock with the frequency of surveillance, with low power consumption reduction of hardware, software power-down mode with the internal latch address and IRQ line, parallel microprocessor interface automatically detect the type of authentication, as well as support for the Ware family Fast CRYPTOI features such as encryption algorithm, which makes MF RC500 more suitable for the reader to the development and high-end security.
2.2 hardware design
Radio-frequency RFID reader hardware circuit shown in Figure 2. In order to drive the antenna, MF RC500 through TX, and 2 pieces of 13.56 MHz to provide the energy carrier. According to the register set up for sending data to be sent the signal modulation. RF card using RF field to carry out in response to the load Modulation. Pick up the signal through an antenna matching circuit to die prematurely RX feet. MF RC500 to the internal receiver signal detection and demodulation according to the register set up to deal with, and then send the data to the parallel port read by the microcontroller. Arising from the use of the internal circuit voltage VMID as the RX-pin input voltage. In order to provide a stable reference voltage, in the VMID pin and access should be between a capacitor, and the RX-pin VMID between the need to access a partial pressure resistance, and, with the antenna in pressure between the resistance of a people Series capacitor will improve the performance of the circuit.
Figure 2 RFID reader hardware RF circuit schematic
2.3 MW RC-500 and microcontroller parallel interface option
MF RC50 0 in support of different micro-controller interface, its own logic of automatic detection can automatically adapt to the system bus of the parallel interface. Signal chip Select the use of NCS, in the power-on reset or hardware after, MF RC500 will also reset the microcontroller parallel interface mode and check the current type of micro-controller interface, through the reduction and control of post-pin logic level to identify Microcontroller interface. The type of interface from a group of fixed-pin connector to determine, as shown in table 1. This paper chose to reuse the address line of interface types, that is, the address data with time-multiplexing Da - D7 a total of 8-bit bi-directional data bus address. When high for the ALE, will be AD. ADe the address of a person's internal address latches latch, and then by the NRD and NWR on the control signal to the completion of the MF RC500 to read and write.
Table 1 MF RC 500-pin interface and the type of
2.4 ATMEGA162 external circuit design
RFID reader to AVR MCU series ATMEGA162 for the control of the core control. ATMEGA162 bring their own single-chip 8 external memory data / address lines, address latch ALE and WR, RD, can be easily and RC500 the ALE, NWR, NRD direct connection. In addition, it has a 3 external interrupt, 2 serial ports, SPI interface, hardware resource-rich, easy to read and write to the expansion of the functions carried out for the reader of multi-function integrated design leaves room for the rich. ATMEGA162 external circuit shown in Figure 3.
Figure 3 ATMEGA 162 external circuit schematic
3 Reader software system design
The single-chip control of the main program is to initialize MFR C500; on the IC card reading, writing and password to verify, erase, and other operations; MF RC-500 and the interruption of communications processing. This article was on the use of single-chip MF RC500 to initialize, that is the key to the operation of the Register.
3.1 register key settings
In order to enable the reader to work, the completion of the basic data to send, receive functions, the need to register: Register pages, the command register, send control register, FlFO register data, interruption to allow register, InteruptRq two registers, and so on. Register the first order of 7 IFDetectBusy interface is the type of testing status symbol for the 0:00 mark the completion of testing the type of interface. FIFO register data is within 64 Byte FIFO buffers in the data input and output ports. Input output data stream in the FIFO buffer in the completion of the conversion, parallel input output. Intetrupt help register is a sign interrupt request registers. When the interruption of production II Health, the need to register by the relevant flag to determine the type of disruption. Following is a page register, send control register, suspended to allow the register details and settings.
3.1.1 page register
MF RC50 0 A total of 64 register, and register for an 8 per page to register the first page register, the setting shown in Figure 4. His address were 0x00, 0 ", Ox10, Ox18, Ox20, Ox28, Ox30, Ox38o its initial value of 10000000,0 x80. Page select register for the register page through the register to determine set up on the inside page register Addressing the way.
Figure 4 register set up
Use PageSelect to a location, they can register on the page address, PageSelect the contents of the address register as A5, A4, A3 this 3 to 8 addressing, page 7 register may be A2, A1, Ao To choose. The location of 0, register address by the internal address latches to the entire contents of the decision. In this paper, the Register addressing the use of the manual MF RC500 is given absolute register addresses, so all pages of the register page of The purchase will be 0.
3.1.2 send control register
Send register control, set it as shown in Figure 5. MF RC500 control of the two antenna pin TX1, and the TX2 on the type of output signal, which is located at 0x11, the initial value of 01011000,0 x58
Figure 5 send control register set up
T X2CW position to 0, TX2 pin on the output signal is 13.56M Hz modulation of the carrier. TX2RFEn will buy 1, TX2 pin on a modulated output of 13.56 MHZ data transmission carrier. TX1RFEn will position 1, TX1 pin on a modulated output of 13.56 MHz data transmission carrier.
3.1.3 allowed to interrupt register
MF RC50 0 with a timer interrupt, interrupted to send, receive interruption, such as interruption of idle 6 interrupt source. The interruption to allow the register can be set so as to interrupt request. SetIEn allow for the interruption, the 1 o'clock position, the other register in place effective control of the interruption. TimerlEn, TxIEn, Rx lEn were allowed to interrupt timer, send and receive suspended to allow interruption of admission control, as shown in Figure 6. Interruption to allow the address to register 0x06, the initial value of OOOOOOOO, Ox00o
Figure 6 interrupt register set up to allow
3.2 system software design
According to the register of the above-mentioned operations, system software can be designed to process as shown in Figure 7. In accordance with this process, the reader can complete an electronic tag read and write basic operation.
Figure 7 software flow chart
Upon completion of read and write operations on the basis of the system software and add a rich, can read and write in all the antenna in a field within the scope of RFID, through the cycle of conflict prevention, has been one of the RFID serial number, select Label to verify this, after the passage of memory to operate. Typical operating time of not more than 100ms
In this paper, the design of radio-frequency RFID reader fully integrated hardware, software advantages can be achieved IS014443A agreement on the Mifare one card read and write, read and write distance of up to 6 cm. If reasonable design and optimization of antenna systems, but also a 9 to 10 cm. The reader can easily with the PC, including the serial port to connect devices, easy targets for different applications embedded into other application of radio frequency identification system. As the controller of the selected program for the Flash memory cell to store, re-programming, easy to upgrade. The reader has a low-cost, fast response, stable and reliable communications, to facilitate the operation of the advantages, applications are also broad prospects for the promotion of RED important.
The first author of the South Zhongliang men born in 1965, is now a precision instruments and Tianjin University College in Optoelectronics Engineering Ph.D., associate professor of reading; mainly engaged in photoelectric detection and computer vision technology, detection technology and systems.
Radio Frequency Identification RFID (radio frequency identifiestion) is the 1990s, the rise of a non-contact automatic identification technology, its use of radio-frequency signal space coupling of the transmission characteristics, can be identified for automatic identification of objects. No need for physical contact with the process of identification, no need for optical visual, no need to manually manage to complete the information recorded and dealt with. Use of RFID technology, can achieve the goal of the campaign, multi-target identification. At the same time, RFID can read and write, be able to carry large amounts of data, confidentiality strong, and has a fear of stains, dust, and other strong environmental adaptability. It is for these other know another way unmatched advantages, RFID technology in production, logistics, communications, transportation, medical, security and other fields have a wide range of applications and great prospects for development. In RFID systems, radio frequency identification tag reader is the collection of information will give background information processing system, key equipment, ensuring a reliable RFID system plays an important role in the work. This article will be Philips's MF RC500 chip at the core of a design to AT-MEGA162 MCU controller for the radio-frequency RFID reader. It completed its Mifare one card for all to read and write and control of the operation, and can be easily embedded into other systems (such as access charges), to become part of the user's system.
1 RFID system and the basic principles of
RFID systems in general by the electronic tag, reader, the computer component of the background. RFID, also known as radio frequency tags, transponders or vector data; reader, also known as the first time, or to read out the communication device (RFID depends on whether the data can be rewritten wireless). RFID reader and, through the coupling radio-frequency signal components to achieve the space (no contact) coupling; coupling in the channel, based on timing relations and realize the energy transmission and data exchange, and then by the computer back to the time The read-write data storage and management analysis trio R FID operation of the basic components of the system as shown in Figure I.
Figure 1 RFID system, the basic component of
Working hours system, a reader in the region emit electromagnetic wave (the size of the region depends on the frequency and antenna size), have a label inside the LC series resonant circuit, the frequency reader with the launch of the same frequency. When the RFID reader through an effective regional electromagnetic waves, electromagnetic waves in the incentive, the labels have a resonance LC resonant circuit, resulting in induction charge accumulated to a certain extent, the capacitor can be used as power for other circuits to provide voltage, The card will launch the data out or receive data reader to the card reader to receive data, decoding and error checking to determine the validity of the data, and then, through the RS-232, RS-422, RS - 485 or wirelessly transmit data back to the computer, data processing.
RFID system standardization and development of high and low efficiency of the system can be widely used in the primary factor. At present, the production of RFR〕 Most of the products using their own standards, the international community have not formed a unified standard. Now, for the use of RFID standards have several "S010536, 5014443, IS015693 and L9018000. Which is the most widely used LSO14443, by the standards of the physical characteristics of the RF power and signal interface, initialization and anti-collision Transfer Protocol, as well as four parts. Because of the Philips family of RFID chips, MF RC500 can IS014443A support of all levels to facilitate the development of the system, the use of the MF RC500 can greatly enhance the reader's efficiency in the development and the formation of a unified standard.
2 reader hardware system design
Radio-frequency RFID reader hardware, including the main microprocessor circuit AT-MEGA162, MF RC500, antenna circuit, and so on. A few of them to read and write RFID chip MF RC500 is the core of the reader, it will complete the reading and writing e-label all the necessary functions, including RF signal generation, modulation, demodulation, security certification and anti-collision, and so on. MCU microprocessor through the core of MFR C501〕 special memory read and write registers to control the MF RC500. MF RC500 is actually between the MCU tag with the electronic exchange of information of the media. Any labels are required to read and write data to pass through the MF RCS00. Send different types of instructions to the MF RC500, on the MF RC500 will be able to achieve control.
2.1 MF RC500 features introduced
MF RC5 00 advanced modulation and demodulation concept of a fully integrated in 13.56 M Hz under all types of passive non-contact and communication protocol. Its internal transmitter do not need to increase the active part of the circuit will be able to drive directly from the operation near the antenna, up to 100 mm; part of the receiver to provide a strong and effective demodulation and decoding circuitry for IS014443A compatible transponder signal; digital IS014443A part of the frame and handle error detection (and the odd-even CRC). In addition, it has a clock with the frequency of surveillance, with low power consumption reduction of hardware, software power-down mode with the internal latch address and IRQ line, parallel microprocessor interface automatically detect the type of authentication, as well as support for the Ware family Fast CRYPTOI features such as encryption algorithm, which makes MF RC500 more suitable for the reader to the development and high-end security.
2.2 hardware design
Radio-frequency RFID reader hardware circuit shown in Figure 2. In order to drive the antenna, MF RC500 through TX, and 2 pieces of 13.56 MHz to provide the energy carrier. According to the register set up for sending data to be sent the signal modulation. RF card using RF field to carry out in response to the load Modulation. Pick up the signal through an antenna matching circuit to die prematurely RX feet. MF RC500 to the internal receiver signal detection and demodulation according to the register set up to deal with, and then send the data to the parallel port read by the microcontroller. Arising from the use of the internal circuit voltage VMID as the RX-pin input voltage. In order to provide a stable reference voltage, in the VMID pin and access should be between a capacitor, and the RX-pin VMID between the need to access a partial pressure resistance, and, with the antenna in pressure between the resistance of a people Series capacitor will improve the performance of the circuit.
Figure 2 RFID reader hardware RF circuit schematic
2.3 MW RC-500 and microcontroller parallel interface option
MF RC50 0 in support of different micro-controller interface, its own logic of automatic detection can automatically adapt to the system bus of the parallel interface. Signal chip Select the use of NCS, in the power-on reset or hardware after, MF RC500 will also reset the microcontroller parallel interface mode and check the current type of micro-controller interface, through the reduction and control of post-pin logic level to identify Microcontroller interface. The type of interface from a group of fixed-pin connector to determine, as shown in table 1. This paper chose to reuse the address line of interface types, that is, the address data with time-multiplexing Da - D7 a total of 8-bit bi-directional data bus address. When high for the ALE, will be AD. ADe the address of a person's internal address latches latch, and then by the NRD and NWR on the control signal to the completion of the MF RC500 to read and write.
Table 1 MF RC 500-pin interface and the type of
2.4 ATMEGA162 external circuit design
RFID reader to AVR MCU series ATMEGA162 for the control of the core control. ATMEGA162 bring their own single-chip 8 external memory data / address lines, address latch ALE and WR, RD, can be easily and RC500 the ALE, NWR, NRD direct connection. In addition, it has a 3 external interrupt, 2 serial ports, SPI interface, hardware resource-rich, easy to read and write to the expansion of the functions carried out for the reader of multi-function integrated design leaves room for the rich. ATMEGA162 external circuit shown in Figure 3.
Figure 3 ATMEGA 162 external circuit schematic
3 Reader software system design
The single-chip control of the main program is to initialize MFR C500; on the IC card reading, writing and password to verify, erase, and other operations; MF RC-500 and the interruption of communications processing. This article was on the use of single-chip MF RC500 to initialize, that is the key to the operation of the Register.
3.1 register key settings
In order to enable the reader to work, the completion of the basic data to send, receive functions, the need to register: Register pages, the command register, send control register, FlFO register data, interruption to allow register, InteruptRq two registers, and so on. Register the first order of 7 IFDetectBusy interface is the type of testing status symbol for the 0:00 mark the completion of testing the type of interface. FIFO register data is within 64 Byte FIFO buffers in the data input and output ports. Input output data stream in the FIFO buffer in the completion of the conversion, parallel input output. Intetrupt help register is a sign interrupt request registers. When the interruption of production II Health, the need to register by the relevant flag to determine the type of disruption. Following is a page register, send control register, suspended to allow the register details and settings.
3.1.1 page register
MF RC50 0 A total of 64 register, and register for an 8 per page to register the first page register, the setting shown in Figure 4. His address were 0x00, 0 ", Ox10, Ox18, Ox20, Ox28, Ox30, Ox38o its initial value of 10000000,0 x80. Page select register for the register page through the register to determine set up on the inside page register Addressing the way.
Figure 4 register set up
Use PageSelect to a location, they can register on the page address, PageSelect the contents of the address register as A5, A4, A3 this 3 to 8 addressing, page 7 register may be A2, A1, Ao To choose. The location of 0, register address by the internal address latches to the entire contents of the decision. In this paper, the Register addressing the use of the manual MF RC500 is given absolute register addresses, so all pages of the register page of The purchase will be 0.
3.1.2 send control register
Send register control, set it as shown in Figure 5. MF RC500 control of the two antenna pin TX1, and the TX2 on the type of output signal, which is located at 0x11, the initial value of 01011000,0 x58
Figure 5 send control register set up
T X2CW position to 0, TX2 pin on the output signal is 13.56M Hz modulation of the carrier. TX2RFEn will buy 1, TX2 pin on a modulated output of 13.56 MHZ data transmission carrier. TX1RFEn will position 1, TX1 pin on a modulated output of 13.56 MHz data transmission carrier.
3.1.3 allowed to interrupt register
MF RC50 0 with a timer interrupt, interrupted to send, receive interruption, such as interruption of idle 6 interrupt source. The interruption to allow the register can be set so as to interrupt request. SetIEn allow for the interruption, the 1 o'clock position, the other register in place effective control of the interruption. TimerlEn, TxIEn, Rx lEn were allowed to interrupt timer, send and receive suspended to allow interruption of admission control, as shown in Figure 6. Interruption to allow the address to register 0x06, the initial value of OOOOOOOO, Ox00o
Figure 6 interrupt register set up to allow
3.2 system software design
According to the register of the above-mentioned operations, system software can be designed to process as shown in Figure 7. In accordance with this process, the reader can complete an electronic tag read and write basic operation.
Figure 7 software flow chart
Upon completion of read and write operations on the basis of the system software and add a rich, can read and write in all the antenna in a field within the scope of RFID, through the cycle of conflict prevention, has been one of the RFID serial number, select Label to verify this, after the passage of memory to operate. Typical operating time of not more than 100ms
In this paper, the design of radio-frequency RFID reader fully integrated hardware, software advantages can be achieved IS014443A agreement on the Mifare one card read and write, read and write distance of up to 6 cm. If reasonable design and optimization of antenna systems, but also a 9 to 10 cm. The reader can easily with the PC, including the serial port to connect devices, easy targets for different applications embedded into other application of radio frequency identification system. As the controller of the selected program for the Flash memory cell to store, re-programming, easy to upgrade. The reader has a low-cost, fast response, stable and reliable communications, to facilitate the operation of the advantages, applications are also broad prospects for the promotion of RED important.
The first author of the South Zhongliang men born in 1965, is now a precision instruments and Tianjin University College in Optoelectronics Engineering Ph.D., associate professor of reading; mainly engaged in photoelectric detection and computer vision technology, detection technology and systems.
