| RFID is essentially a kind of wireless communication technique. Its receiving terminal can identify the target via reading the information delievered by its transmitting terminal. In practical applications, the electronic tags are divided into three types: passive tags, semi passive tags and active tags.Compared with passive tags, active tags have lower transmission power, longer communication distance, greater data transmission capacity, higher reliability, and greater compatibility.However, the application of active tags is constrained by its built-in battery life. How to improve battery life and reduce the power consumption of active tags is an extremely challenging work.Reducing active tags power consumption is an effective way to improve battery usage, but it did not improve battery life. Harvesting energy from solar energy is a good way to solve this problem, but those collected energy must be sufficient.In order to solve the above problems, the main research contents and work are as follows:First, several energy harvesting technique are analyzed. After analyzing the environmental energy in detail, this thesis decides to use solar energy harvesting technique. As long as the tag works under the lighting, the energy can be harvested and stored in the energy storage unit.Second, the power management module is designed. After analyzing various energy storage devices in detail, the rechargeable lithium battery is selected as the energy storage unit. The design boosts the voltage of harvesting energy for lithium battery charging, and monitors real-time battery status. When the battery is in an overvoltage condition, the design will stop charging the battery; when the battery is in an undervoltage condition, the power supply of the system is cut off to protect the battery.Third, the BLE hardware is designed. After analyzing a variety of wireless communication protocols in detail, BLE is selected as the communication protocol of this design. After selecting the communication protocol, the DA14580 chip is used as the main chip, and a PCB printed antenna is selected for it. The design has the characteristics of far communication distance and low power consumption. This module is the core part of the whole active tag. It is responsible for the wireless communication and positioning of the terminal equipment.Fourth, the active tag software and terminal software are designed. After analyzing i Beacon communication protocol in detail, C language is used to write the i Beacon program, and the software meets the requirements of low power consumption.Java language is used to develop an application to recognize the active tag. The terminal software has the function of displaying the communication information and distance measurement.After the design is finished, the function and performance of the active tag are tested, and the test data of the active tag is given. Test data show that the active tag works well and meets the design requirements. The active tag can always work under enough sunlight conditions,and this thesis solves the problem of active tag battery replacement. |
