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1. Project overview
1.1 Introduction
By the beginning of the 21st century, RFID has ushered in a new period of development, and its value in the civilian field has begun to receive widespread attention from all over the world. RFID (Radio Frequency Identification), that is, radio frequency identification. RFID radio frequency identification is a non-contact automatic identification technology, which automatically recognizes the target object and obtains relevant data through radio frequency signals. The identification work does not require manual intervention and can work in various harsh environments. RFID technology can identify high-speed moving objects and can identify multiple targets at the same time, and the operation is quick and convenient.
1.2 Project background/motivation for topic selection
Mobile phones have become an indispensable part of people’s lives. As a result, cases of theft of mobile phones in life often occur. Especially expensive mobile phones are the target of thieves. The theft of a mobile phone brings not only money, but also the loss of important information in the mobile phone. The anti-theft of mobile phones slowly entered people’s field of vision. RFID technology can well realize the function of mobile phone anti-theft.
2. Demand analysis
2.1 Functional requirements
This design of mobile phone anti-theft accomplishes the following tasks:
First: Timely anti-theft
Second: Pursuit of stolen mobile phones
Third: prevent mobile phones from being left behind
Figure 1 System architecture
2.2 Performance requirements
When a thief connects in abnormal situations and touches the mobile phone, it is enough to inform the owner of the phone as soon as possible
Confirm that the mobile phone is stolen, provide information, and quickly locate the target mobile phone
The phone leaves a certain range to remind the owner that the phone may be dropped
Provide enough useful information interface
3. Scheme design
3.1 Principles of system function realization
Under normal use. There is an RFID tag in the hand. When the phone is touched with legal authority, the phone can be used normally. When a thief or other abnormal situation accesses and touches the mobile phone, the surrounding temperature of the mobile phone will change accordingly. Comparing the mobile phone’s device with information. When the abnormal situation is confirmed, it is judged that there is a risk of theft, and the user is reminded to send out prompts and alarms.
Second: Pursuit of stolen mobile phones
When the mobile phone is accidentally stolen away from the head of the household and exceeds the set range, the handheld device will remind the user to react. When the user determines that the phone is stolen, it enters the RFID distance measurement mode. The mobile phone owner can retrieve it based on the distance between the mobile phone and himself. In this way, the mobile phone can be quickly located, and the mobile phone can be retrieved in the first time. When the direction that the owner is looking for is opposite to the direction of the phone, it can show the expansion of the distance. When the direction of the owner and the phone are the same, it can show that the distance is close, which can guide the owner’s search well.
Third: But set the distance between man and machine, which can remind the phone owner when the phone is left behind, effectively preventing the phone owner from leaving the phone. So that the mobile phone can get the best protection.
3.2 Hardware platform selection and resource allocation
The evaluation kit and development system EVK1100 based on the AVR32 AT32UC3A microcontroller are selected.
AVR32 AT32UC3A has a single-cycle RISC instruction system to meet the needs of communication and high-speed data processing.
With reading and writing and address latching allow control pins, it is convenient to expand and use external interfaces and external storage space, and it is convenient to connect the communication unit.
3.3 System software architecture
1. The program modularization of each module;
2. The main program judges whether the mobile phone has an abnormal state;
3. Handling of abnormal conditions;
4. Setting of safety distance;
5. Temperature collection;
6. Setting of human-computer interaction interface;
7. Consolidation of security.
3.4 System software process
Program operation flow chart
3.4 Expected results of the system
The wireless radio frequency transceiver and ranging module adopts NanoPAN module of Nanotron Company. The module uses broadband chirp spread spectrum (CSS) technology and is adopted by the IEEE 802.15.4a standard. The transceiver is a 2.4 GHz ISM band wireless device, which can flexibly provide a data transmission rate ranging from 31 25 Kb/s to 2 Mb/s. Its point-to-point ranging accuracy is high, and it can provide reliable data with an excellent transmission range at the same time Communication. By adopting a MAC controller, the requirements for microprocessor and software can be reduced, and the design of high-level systems can be easily completed. This module is one of the important core parts. The focus of anti-theft. Finally, the device achieves a high level of anti-theft.
Design works add a simple human interaction interface.
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