The Cpu-buss Based On Scpu-dbus Architecture Bridges The Design And Realization

sCPU-dBUS architecture is a new kind of architecture aimed at reducing the security vulnerability of embedded system,and is single CPU dual bus architecture,sCPU-dBUS employs two buses,local bus and net bus,replaces the only one system bus in current architecture.The system is separated into two parts by dual bus:local sub-system and net sub-system.The local sub-system includes local storage module,and the net sub-system contains net module and storage module.It's required that local sub-system and net sub-system are separated in sCPU-dBUS,so danger from network can not harm the local storage,and the security of embedded system is improved.To fulfill to security requirement,A CPU-BUSs bridge for sCPU-dBUS is designed and implemented in this paper.The function of CPU-BUSs bridge is to make sure that only one of the two buses(local bus or net bus) is connected to CPU at the same time,the local sub-system and the net sub-system are separated.When CPU needs to connect the other sub-system,the CPU-BUSs bridge can cuts current connection and connects CPU with the other sub-system.The design of the CPU-BUSs employs SoC technology,and follows the standard of SoC bus.The CPU-BUSs bridge is divided into three layers:the physical layer,the hardware abstraction layer and the kernel layer,based on hierarchical model of embedded system.The functions of the physical layer include design,implement and emulation of the hardware logic of CPU-BUSs.The functions of the hardware abstraction layer is to drive the physical layer,and encapsulate the hardware logic of the CPU-BUSs.The functions of the kernel layer consist the modification ofμC/OS-Ⅱtask distribution strategy,and the flow of changing sub-systems.Each layer offers relevant protocols to the higher layer.In the end,a system experiment,which tests the function of the CPU-BUSs,is given in this paper. The result shows that the CPU-BUSs can separate the local sub-system and net sub-system,and change the connection between CPU and sub-systems.The CPU-BUSs meets the requirement of the sCPU-dBUS,and enhance the security of the embedded system.