The design of electronic license plate recognition terminal system based on n_rf24le1
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The document describes an electronic license plate recognition system using RFID technology. It consists of reader modules and electronic license plates (E-plates). The reader module uses an ARM chip and RF circuit to communicate with E-plates. E-plates are based on the nRF24LE1 RF chip and transmit vehicle data like plate number when in range of the reader. The system software uses FreeRTOS for reader control and a communication protocol to transmit encrypted data between readers and E-plates.
The design of electronic license plate recognition terminal system based on n_rf24le1
- 1. The Design of Electronic License Plate Recognition Terminal System based on nRF24LE1 2012 Fifth International Symposium on Computational Intelligence and Design Wei Chen, Jianding Yu, Xiangjun Liu Emp, CHEN stu9458@gmail.com
- 2. Ajenda • Introduction • System structure • Hardware design – Reader module – Electronic tag • Software design – Reader module – Electronic tag • Conclusion
- 3. Introduction
- 4. Introduction • The limited Land resources and economy is a big challenge for the urban road construction. • ITS(Intelligent Transportation Systems) • The RFID technology has advantage in long-range identification, carrying more information, reading data rapidly and wide application
- 6. System structure • The system consists of reader, electronic license plate(E-Plate) and host computer management system. • When the vehicle, which has been installed electronic license plate, enters the range of the reader.
- 7. Analysis and Store Communication
- 9. Hardware design • Reader module –ARM chip, RF(Radio frequency), Control circuit. • E-plate module – Wireless RF application circuit. – Base on nRF24LE1 – Some peripheral
- 10. Hardware design • Reader Module –LM3S8962 • Cortex M3、50MHz、36 Interrupts、Cheap(?) • Main –Process、Memory 、Power conversion • Extended –RF(Communication by I2C)、JTAG 、LCD+Touch 、 LED…
- 11. Hardware design • RF circuit - receive the information from E-plate and send to the processor through the mode of I2C. • Processor deals with the received information and sends to the PC • LCD&TS - human-computer interaction
- 12. Hardware design Program To PC To E-plate Date
- 13. Hardware design • E-Plate (nRF24LE1) – 8051F + nRF24l01P – The stability and reliability of the RF system is increased and the cost is reduced – ISM Frequency band from 2.4GHz to 2.5GHz – Maximum transmission rate 2Mbit/s – Distance 100m (Without sleep)
- 15. Software design
- 16. Software design • Reader – The real-time operating system FreeRTOS is used for the reader control – The TCP / IP protocol stack has been ported to the FreeRTOS
- 17. Software design Step1: Initial the nRF24LE1. Configure to TX mode. Step2: Button is pressed, the nRF24LE1 sending corresponding commands. Step3: If successfully received, displayed on the LCD. Else if fails, Timeout will be determined.
- 18. Software design • E-plate – Use button batteries – E-plate not work until an interrupts – The E-plate will process the received information in a short time, and then work on low power consumption module as soon possible.
- 19. Software design
- 20. Software design • Communication protocol – SGN(signture) – CMD(Command) – TID(Tag identifier) – UID(User identifier) – STA(Status)
- 21. Software design • Encryption – DES • F-function • 56bits key. • 64bits block
- 22. Conclusion • The hardware circuit main chip is RF chip nRF24LE1 and LM3S8962, which is based on the kernel of CORTEX-M3. • The software includes tag data, receiving data and sending data, and also encryption algorithm.
Editor's Notes
- #8: 當進入Reader的範圍後，Reader即可傳送「讀與寫」的指令。而後E-plate將會等待Reader傳送信息給予自己，並回傳信號給予Reader。 Reader會處理接收到的確認碼信息。而後開始接收儲存在E-plate上的資料。 最後，這些資料處理完畢後將藉由網路傳送給PC端。
- #11: LM3S8962 大約16.09美金 板子上使用JTAG, 為IEEE 1149.1通信協定
- #14: Nrf24le1價格：純ＩＣ價格25元、整塊開發版大約150元
- #18: 初始化Nrf24le1的模組，並將之轉到TX狀態 傳送按鈕按下則傳送對應指令 若Reader聽到了E-plate的信息，信息將會顯示在LCD上。如果失敗則會確認是否逾時，如果沒有逾時則會等待回傳。
- #20: 初始化nrf24le1模組並且將之轉換成RX模式，等待從Reader來的指令。 如果傳送過來錯誤，則睡0.5秒。如果沒問題則轉到TX狀態並且確認通道是否空閒。如果並非空閒則等待隨機的時間（不到一秒）。 空閒則發送信號，並確認發送信號是否成功，如果失敗則重新等待信號（代表本次不算，為了避免信息過舊所以並無重傳）
- #22: DES是一種典型的塊式密碼，將固定的內容透過一系列複雜的操作變成同樣長度的密碼。一塊是64BITS。