Design And Implementation Of PCIe Transaction Layer Based On AXI Bus

Bus system is a crucial component of computer system.The bus system is responsible for the exchange of information between various components of the computer and the coordination of the functions of various modules.In the development of bus technology,there have been three generations of bus technology.Every update of bus technology provides new impetus for the development of computers.PCI Express bus is the most widely used system bus technology with the best performance,and its importance is self-evident.As a part of the PCIe bus protocol that is closest to the user application layer,the implementation of the PCIe transaction layer is one of the core tasks in PCIe design.In practical applications,a very common architecture design for systems on chip is to use on-chip buses such as AXI for internal interconnection and information exchange with external interface buses such as PCI Express.Therefore,the design of the PCI Express transaction layer and the completion of the protocol conversion process from PCI Express to AXI and other on-chip buses are crucial parts of PCI Express system design.This article is divided into three parts: theory,design,and verification.In the theoretical part,this article introduces the relevant concepts of the PCIe protocol,focusing on the PCI Express transaction layer,including the functions of the transaction layer,the structure of the transaction layer package,the transaction layer credit management,and power consumption management,especially the flow control related mechanisms based on credit values.In addition,this article also briefly introduces the structure and transmission process of the AXI bus protocol,including the burst transmission of AXI and the handshake process.In the design part,according to the IC design process,this article has carried out the design work of the PCI Express transaction layer,including the receiving part,the sending part,and other related modules of the transaction layer.Among them,the implementation of flow control mechanisms and the implementation of PCIe receiving and sending sequencing rules are relatively difficult issues in the design process.In addition,this article also implements the protocol conversion process from PCI Express bus to AXI bus,and addresses some related issues that arise when transactions are transmitted between different buses,including the issue of maintaining the order of transaction protocols,the generation and processing of PCIe requests,and the interconnection between PCIe related modules and AXI.In the verification section,this article uses VCS and Verdi as verification tools,and uses a bus functional model to assist in building a verification platform,significantly reducing the workload of verification work.A complete verification of the PCI Express transaction layer designed based on the AXI bus protocol was performed,and good results were obtained.