CN206193856U - Food safety traceability system based on RFID technique - Google Patents

Abstract

The utility model relates to a food safety traceability system based on RFID technology, an MCU unit for computing and processing data; a display for displaying computing data; a prompt unit for generating voice prompt information; The radio frequency identification unit that drives the reader antenna to communicate with the transponder to realize reading, decoding and writing; the antenna used to generate magnetic flux to provide energy to the passive tag and establish a connection between the tag and the reader; used to communicate with the reader The reader performs password verification and reads and writes the ID card of the card. Track the place of origin of the food, the production date of the food, that is, the shelf life of the food according to the food number. It can improve the organizational structure of producers, operators and consumers, and solve the untimely information transmission caused by technical limitations. At the same time, the construction of a food safety system based on legal and moral constraints can also be strengthened to ensure the accuracy of information.

Description

A food safety traceability system based on RFID technology

technical field

The utility model belongs to the technical field of food safety, in particular to a food safety traceability system based on RFID technology.

Background technique

In recent years, food safety has aroused the close attention of the general public. Especially after the frequent occurrence of multiple types of food safety incidents, people began to realize the importance of food safety. At the same time, food safety has also attracted great attention from the Party Central Committee and the State Council, and people's health and life safety have always been regarded as the top priority. As the development of the current food chain system is becoming more and more complex, there are many procedures from food production to packaging, so the unsafe factors of food are also increasing. These processes have led to frequent food safety incidents around consumers, causing consumers to lose confidence in food safety, and seriously affecting social stability and consumer health.

Food safety researchers divide food safety into three aspects: quantity safety, sustainable safety and quality safety. The most important of these is quality and safety. Food quality and safety mainly refers to the high nutritional quality of food, which can meet the nutritional needs of the eating population and ensure the health of the eating people. For these reasons, when a food product enters the market, the food label it carries plays a vital role. At the same time, relevant departments have also made strict regulations on the standardization of food labels.

The food traceability control system, that is, the tracking and traceability system for food safety, is currently known as an effective way for food management departments or consumers to control and monitor food safety. However, up to now, there is still no international authoritative definition to describe the traceability of food.

Since RFID technology is currently widely used in production, transportation, medical treatment, anti-counterfeiting, etc., but its application in food is developing very slowly, mainly including the following aspects:

1. The cost is too high

Tags based on RFID technology are different from commonly used barcodes or the emerging two-dimensional codes, which contain tiny integrated circuits inside. Therefore, compared with barcodes or two-dimensional codes, its production cost is high. If RFID technology is applied to low-priced commodities, the costs of producers, sellers and consumers will all increase. The price factor largely determines that electronic tags cannot be widely used in various consumer goods.

2. Complicated data entry

In the food industry, it has the characteristics of diverse types, complex sources of raw and auxiliary materials, and short-term transportation diversity. If the product information is continuously entered in each process, it will inevitably increase the workload of workers. From this aspect alone, it hinders the development of RFID technology. Moreover, in the process of data entry, the accuracy of information entry and the rigor of workers cannot be effectively guaranteed, which also makes the development of this technology meaningless.

Contents of the invention

The utility model provides a food safety traceability system based on RFID technology with simple structure, convenient installation and use, and improved work efficiency in order to solve the problems of high cost of RFID technology and complicated data entry in the known technology.

The technical scheme that the utility model takes for solving the technical problem existing in the known technology is:

The food safety traceability system based on RFID technology includes:

MCU unit for computing and processing data;

A display connected to the MCU unit for displaying calculation data;

It is connected with the MCU unit and is used to generate a prompt sound unit for voice prompt information;

Two-way connection with the MCU unit, used to drive the reader antenna to communicate with the transponder, and realize the radio frequency identification unit of reading, writing, decoding and writing;

Two-way connection with the radio frequency identification unit, used to generate magnetic flux to provide energy to the passive tag and establish an antenna connecting the tag and the reader;

Connected with the radio frequency identification unit, it is used for password verification with the reader, and an ID card for reading and writing operations on the card.

Further, the radio frequency identification unit is composed of a card reader antenna, an electronic tag, and an RFID controller, and the electronic tag is connected to the RFID controller through the card reader antenna.

Further, a buzzer is installed inside the prompt sound unit.

The utility model tracks the production place of the food, the production date of the food, that is, the shelf life of the food according to the food serial number. It can improve the organizational structure of producers, operators and consumers, and solve the untimely information transmission caused by technical limitations. At the same time, the construction of a food safety system based on legal and moral constraints can also be strengthened to ensure the accuracy of information.

Description of drawings

Fig. 1 is the structural representation of the food safety traceability system based on RFID technology that the utility model embodiment provides;

Fig. 2 is the minimum circuit system diagram of the single-chip microcomputer that the utility model embodiment provides;

Fig. 3 is the MCU unit and the display connection circuit diagram that the utility model embodiment provides;

Fig. 4 is a circuit diagram of the antenna provided by the embodiment of the present invention;

In the figure: 1. MCU unit; 2. Display; 3. Radio frequency identification unit; 4. Prompt tone unit; 5. ID card; 6. Antenna.

detailed description

In order to further understand the invention content, characteristics and effects of the present utility model, the following examples are given, and detailed descriptions are given below in conjunction with the accompanying drawings.

Below in conjunction with Fig. 1 to Fig. 4, the structure of the utility model is described in detail.

The main control chip used by MCU unit 1 is the STC89C52 chip produced by STC Company. This chip is a low-power, high-performance CMOS 8-bit microcontroller, commonly known as a single-chip microcomputer. At the same time, the chip has 8k Flash memory that can be programmed in the system. The STC89C52 single-chip microcomputer has functions that the traditional 51 single-chip microcomputer does not have, but it is also compatible with all functions of the traditional 51 single-chip microcomputer. Because it has an 8-bit CPU, it can be programmed flexibly on a single chip. The minimum circuit system of the STC89C52 microcontroller is shown in Figure 2. The structure of the minimum circuit system mainly includes: a reset circuit, an oscillation circuit and a memory selection circuit.

The STC89C52 single-chip microcomputer has the following characteristics: The single-chip microcomputer has a total of 40 pins: among them, the power supply, reset circuit, power supply, grounding and EA each occupy 1 pin; the crystal oscillator circuit occupies 2 pins; 32 IO interfaces; 2 are suspended pin. STC89C52 single-chip microcomputer is 8k bytes Flash on-chip program memory, 256 bytesde random access memory (Random Access Memory, RAM), with 32 external bidirectional input/output interfaces (I/O), 5 interrupt priorities, and 2 16-bit programmable Timing counter, 2 full-duplex serial communication ports, watchdog (WDT) circuit, on-chip clock oscillator.

1. Single-chip power supply circuit: Generally, the power supply for the STC89C52 single-chip microcomputer is 5V. In Figure 2, VCC and GND are the power supply network identifiers.

2. Crystal oscillator circuit: 24MHz crystal oscillator is used as the clock source of the STC89C52 microcontroller.

3. Reset circuit: It is an important part of the normal operation of the single-chip microcomputer. The reset circuit should ensure that the single-chip microcomputer is effectively reset at the moment of power-on. When the single-chip microcomputer is working normally, the RST pin needs to be connected to low level.

According to the pin function of STC89C52 microcontroller, it can be divided into four aspects for introduction:

1. Power pin

VCC(40): Connect to the positive terminal of 5V power supply;

GND(20): Connect to the positive terminal of 5V power supply.

2. External crystal oscillator pin

XTAL1 (19): Inside the microcontroller, XTAL1 is equivalent to the input of an inverting amplifier. When connecting with an external clock, the access method of this pin is different for different microcontrollers. For example, when connecting with an HMOS microcontroller, it needs to be grounded; when connecting with a CHMOS microcontroller, it is the access terminal for external signals.

XTAL2 (18): The output of the inverting amplifier connected to the internal oscillator in the microcontroller. This pin operates similarly to XTAL1(19). When it is connected with HMOS, it is an input terminal; when it is connected with CHMOS, it only needs to be suspended.

3. Control signals or multiplexed pins with other power supplies

There are 4 forms of this type of pins, namely: RST, ALE, PSEN and EA.

1) RST (9): the reset key. It acts as the electrical reset terminal and power-down protection terminal on the single-chip microcomputer. If the single chip microcomputer is in the period of oscillation, this pin can help the single chip microcomputer reset to the initial state; when VCC fails, this pin can be connected to the backup power supply to ensure the continuous power supply of the single chip microcomputer, so that the data in the RAM can continue to be saved.

2) ALE (30): When accessing the external memory, ALE (enable address latch signal) is output as a signal twice per machine cycle, and is used to latch the low that appears at the P0 port.

3) PSEN (29): This pin is the strobe output terminal of the off-chip RAM, and it is only valid when it is connected at a low level. During the period when the off-chip RAM reads the signal from the outside, this terminal is valid twice in each cycle, and the command signal can be read through the data bus port. If the off-chip signal is accessed, no signal appears at this end.

4) EA (31): This terminal is the control terminal for accessing the external RAM, and it is only valid when it is connected at a low level. When this end is connected at a high level, the microcontroller accesses the internal RAM 4KB; if it exceeds this range, this end automatically accesses the program of the external RAM. If this end keeps low level all the time, then access the external program memory.

4. Input/Output (I/O) pins P0, P1, P2, and P3

1) P0(39-22): When the chip is not connected to an external circuit or expanded, P0.0-P0.7 can be a quasi-bidirectional 8-bit input/output interface. When the chip contains EPROM single-chip programming, the instruction byte is input from P0, and when the program is checked, the instruction byte is output.

2) P1(1-8): P1.0-P1.7 are collectively referred to as P1 ports, which can be used as quasi-bidirectional I/O ports. For EPROM, when performing programming or program verification operation, P1 port will receive the lower 8-bit address of the input signal.

3) P2 (21-28): P2.0-P2.7 are collectively referred to as P2 ports, which can generally be used as quasi-bidirectional I/O interfaces. Probably when the external program memory is connected or expanded, the P2 port is used for the high 8-bit address bus to send the high 8-bit address. For EPROM programming or program verification, the P2 port receives the input 8-bit address.

4) P3 (10-17): P3.0-P3.7 are collectively referred to as P3 ports. The 8 ports are all dual-function ports, not only as general quasi-bidirectional I/O ports, but also can use each bit for The second function, and each pin of the P3 port can be independently defined as the input and output of the first function or the second function. The second function of P3 port is shown in Table 1.

Table 1 Function table of P3 port

To sum up: the pin functions of the STC89C52 microcontroller can be summarized as:

1) The single-chip microcomputer has many functions and few pins, so most of the pins have the second function;

2) The single-chip microcomputer is in the form of 3 buses externally, and the P2 and P0 ports form a 16-bit address bus; the P0 port is time-division multiplexed as the data bus.

The display 2 adopted in the utility model is an LCD12864 liquid crystal display module, which has 20 pins, including 8 bidirectional data lines and 6 control lines and power lines.

LCD12864 liquid crystal display 2 is divided into left and right screens, with 128 row pixels and 64 column pixels, and the entire screen is 128*64 pixels. The programming of the liquid crystal display 2 is to write data into the DDRAM. Before writing data, the RAM needs to be cleared first, and the left and right screens need to be cleared separately. The pin function table of LCD12864 is Table 2

Table 2 LCD12864 pin function table

LCD12864 liquid crystal display 2 uses a screen with a font library. The 128*64 screen with Chinese characters can display 32 Chinese characters of 16*16 dot matrix in 4 rows and 8 columns. Each display random memory can display 1 Chinese character or 2 A 16*8 dot matrix display of full-height ASCII code characters. Internally with a Chinese character library, it can provide 128*2 bytes of character display RAM buffer. The display of the characters is realized by writing the code into the RAM. According to the difference of written content, Chinese characters, ASCII codes and custom content can be displayed on the LCD screen.

There are two communication modes of the LCD12864 liquid crystal display: serial communication and parallel communication. Due to the fast data transmission speed of parallel communication, the communication method between LCD12864 liquid crystal display and MCU adopts parallel communication.

Display 2 has an overall chip selection signal "E", only when this signal is high level, all circuits will lose their functions. In addition, each of the left and right half screens has a selection signal CS1 and CS2, and when each is at a low level, the left half screen and the right half screen are respectively selected. In order to distinguish whether the content of reading and writing is data or instructions, a data/instruction control line D/I is additionally set up. According to these principles, the interface circuit is designed as shown in Figure 3.

Since the reader-writer chip has registers, the MCU unit 1 can control the reader-writer chip by reading and writing the registers in the reader-writer, and transmit the signal to the prompt tone unit 4 . When the reader/writer receives the signal from the MCU unit 1, it will follow the protocol format of the non-contact radio frequency card to search by sending a fixed-frequency modulation signal with the antenna 6 and other matching circuits. When finding the existence of ID card 5 within this range, the LC resonant circuit in ID card 5 (the frequency of the resonant circuit is consistent with the frequency sent by the reader) will generate resonance under the excitation of electromagnetic waves.

When there is an ID card 5 within the effective working range of the reader, the MCU unit 1 sends a search signal to the card, and the card will return information to establish the first contact between the ID card 5 and the reader. If the frequency sent by the MCU unit 1 When there are multiple ID cards 5 within the range, the reader will start its anti-collision mechanism to ensure the legality of the operation. When this situation occurs, the reader will select one of the cards according to the card number, and the selected card will be verified with the reader, while the unselected card is still in an idle state, waiting for the next time MCU unit 1 sends out a card. The command. After the password verification between the ID card 5 and the reader/writer is successful, application operations such as reading and writing can be performed on the card.

The information transmission method of RFID electronic tags is wireless data transmission. Its main advantage is that data processing can be carried out, and security verification can also be carried out at the same time. When connected with the reader, the RFID tag and the reader will enable a two-way authentication mechanism. Before data processing, the tag needs to be authenticated three times with the reader, and all processes will be encrypted and protected.

The key of the radio frequency identification unit 3 is a radio frequency chip, and the chip selected in the utility model is MFRC522. MFRC522 is a highly integrated read-write card series chip that can be used in 13.5MHz contactless communication. It is a low-voltage, low-cost miniature non-contact read-write chip developed by NXP, which is the best choice for portable handheld devices.

Based on advanced modulation and demodulation concepts, MFRC522 integrates all types of passive non-contact communication methods and communication protocols under 13.5MHz. The internal sending part of the chip can drive the reader-writer antenna to communicate with the transponder, etc., without the assistance of other devices. The receiver part can improve the effective demodulation and decoding circuit for processing the signal at the receiving end. The digital section processes ISO14443A frames and performs parity detection. The chip can support higher-speed contactless communication, and its two-way data transmission rate is also very high. MFRC522 is one of the 13.5MHz high-integration read-write series chips. Its communication with the host adopts serial communication with fewer connections, and it can perform one of SPI, I2C or serial modes according to different user needs. The selection of the species is conducive to reducing the number of connections, reducing the volume of the PCB board, and can also reduce the cost.

MFRC522 can be connected with interfaces of different controller chips. It has automatic detection logic, so it can start adaptive system mode to connect with other interfaces. It is worth noting that although MFRC522 supports different digital interfaces, and its interface forms are diversified, so the chip needs to re-check the connection relationship of the external pins after each reset.

The antenna 6 is mainly used to generate magnetic flux, and the function of the antenna 6 is to provide energy to the passive tag and establish a connection between the tag and the reader. The 13.56MHz RF antenna and matching circuit have three components: coil, LC resonant circuit and EMC filter circuit. In the design of the antenna 6 , ensuring that it generates a strong electromagnetic field is a basic condition for designing the antenna 6 . Its purpose is to enable the card to power itself through the antenna 6 . At the same time, there must be enough passband to transmit the signal and also be a verification standard for the output energy of the antenna 6 .

The resonant frequency formula of antenna 6 is formula (3.1):

Wherein, f is the resonant frequency, L is the equivalent inductance of the antenna 6, and C is the equivalent capacitance. In this thesis, the working frequency of antenna 6 is 13.5MHz. If the equivalent inductance L of antenna 6 is too high, then C should be reduced. The formula for calculating the inductance of the loop antenna 6 is:

In the formula (3.2), I1 is the length of one circle of the loop antenna 6 , D1 is the diameter of the wire, and K is the shape factor of the antenna 6 . N1 is the number of turns of the coil, and P is a coefficient related to the coil structure. The formula for calculating the quality factor Q of antenna 6 is as follows:

Q can be used to evaluate the output efficiency of the loop, the larger its value, the higher the output efficiency of the capacity. If the Q value is too high, the passband will be narrowed, and the energy Fodo at the subcarrier frequency will be too small, which will affect the transmission of the modulated signal.

FIG. 4 is a matching circuit for the antenna 6 and filtering. In the sending part, the signals sent on the pins TX1 and TX2 have 13.5MHz carrier energy modulated by the envelope signal, and drive the antenna 6 through the EMC filter circuit composed of L0 and C0 and the matching circuit composed of C1, C2 and Rq. In the receiving part, R2 and C4 ensure the DC input voltage of the RX pin, and R1 and C3 adjust the AC input voltage of the RX pin.

Put the product ID cards 5 on the induction area respectively, and when the ID cards 5 are put on, the LCD screen will display information such as the name, serial number, ex-factory, and shelf life of the product respectively. The product information in the label can be displayed correctly and the expected design goal can be achieved.

Table 3 Product Performance Table

It can be seen that the working voltage of the system is 3.3V, the working current is 5.0V, and the power consumption of the system is low. Generally speaking, the system has good reliability, is not easy to be damaged, and is easy to use and maintain. At the same time, its cost is small and has High cost performance.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model in any form. Any simple modifications made to the above embodiments according to the technical essence of the present utility model are equivalent to changes and modifications. All belong to the scope of the technical solution of the utility model.

Claims (3)

1. a kind of food security traceability system based on RFID technique, it is characterised in that food security of RFID technique should be based on Traceability system includes：

MCU units for data to be carried out with computing and treatment；

It is connected with MCU units, for the display shown to operational data；

It is connected with MCU units, the prompt tone unit for producing information of voice prompt；

It is bi-directionally connected with MCU units, for driving reading and writing device antenna to be communicated with answering machine, realizes the nothing of read-write, decoding and write-in Line rfid uint；

It is bi-directionally connected with radio frequency identification unit, for producing magnetic flux to provide energy to passive label and setting up label and read Write the antenna connected between device；

It is connected with radio frequency identification unit, for carrying out cryptographic check with read write line, the ID of operation is written and read to card Card.

2. the food security traceability system of RFID technique is based on as claimed in claim 1, it is characterised in that described wirelessly penetrates Frequency recognition unit is made up of card reader antenna, electronic tag, the part of RFID controller three, electronic tag by card reader antenna with RFID controller is connected.

3. the food security traceability system of RFID technique is based on as claimed in claim 1, it is characterised in that described prompt tone Buzzer is installed inside unit.