Circuit Design of PCI Express Retry Mechanisms

TLP retry mechanism is an effective measure of PCI Express to ensure data reliable transmissions. The paper theoretically analyzes reasons for retransmission, operating rules of retransmission and factors affecting the size of retry buffer. On this basis, proposes a circuit structure of implementing TLP retry mechanisms, describing the implementation process of retry management, and conducts functional verification based on VMM verification platform, using VCS simulation tool. Verification results show that this method not only implements the function of the retry mechanisms, but also guarantee data transmission normally and orderly. What’s more, it would save the storage space of retry buffer and improve the efficiency of the link transmission. Key-Words: PCI Express, TLP retry mechanism, Retry buffer, VMM.