The Design And Development Of The Vehicle-mounted OBD Terminal Based On Bluetooth Low Energy

With the rapid development of IOV(Internet of Vehicles)technology,the concept and equipment of automobile wearing gear,vehicle-mounted OBD(On Board Diagnostics)terminal are gradually accepted and used by the public,while enjoying the driving pleasure,people start to pay more attention to some vehicle-releated information,such as fuel consumption,vehicle health status,etc.With the help of mobile internet and OBD intelligent terminal,the owner can take real time control of the vehicle status information.A vehicle-mounted OBD terminal is implemented based on Bluetooth Low Energy(BLE)in this thesis,vehicle bus real time data can be parsed and transferred to smart phone or other mobile device via bluetooth by this terminal,with these data the mobile application can diagnose the vehicle and sample the travel data.To upgrade the OBD terminal wirelessly,an air IAP(In Application Programming)upgrade scheme based on bluetooth SPP(Serial Port Profile)is proposed and implemented in this project.Detailed research contents is described as below:(1)On the basis of deep learning and understanding of the principle and construction of bluetooth low energy technech,technical investigation is been done and the dual mode bluetooth chip TC35661 from Toshiba is chosen as the bluetooth solution for this project.On referencing the offical application manual,circuit is designed to construct the bluetooth module.(2)STM32f407 micro controller is selected as the primary MCU,conbined with TJA1040 T CAN transceiver the OBD module scheme is determined.With the design for MCU basic operation and debug circuit,system power supply circuit and bluetooth chip TC35661,the embedded system hardware platform is established.(3)Embedded real time operation system μC/OS-III is picked and transplanted on primary MCU and an embedded software developing platform is built based on IAR system for ARM,on this platform,the bluetooth chip driver,OBD module dirver,IAP air upgrade driver are designed,OBD and bluetooth application program are written based on the task of μ C/OS-III,realizing the advertising of bluetooth OBD terminal and the OBD data parse and transfer after connection establishment.(4)Bluetooth OBD client application is programed on calling API offered by android system,this application can discover the designed OBD terminal,connect to it,receive the OBD data and display it.Aim at the OBD terminal in application programing,an air upgrade interface is implemented which can upgrade the internal FLASH of the primary MCU,ease the OBD device firmware update for the user.