Modern chip design verification often encounters challenges when connecting peripherals, primarily due to drastic differences in operating speed or hardware limitations. Designs running on hardware emulators or FPGA prototyping platforms typically operate at clock frequencies of tens of megahertz, and in some cases even below one megahertz. In contrast, real-world peripherals and protocols, such as PCIe and high-speed Ethernet, operate at hundreds of megahertz or higher. This significant gap in operating speed makes direct connections between the prototype and peripherals almost impossible.
To address speed mismatches, a common and effective solution is the use of a speed adaptor. A speed adaptor is a specialized hardware interface used in prototyping or emulation environments. Its primary function is to bridge systems that operate at very different speeds. This enables verification leveraging real-world transactions rather than pure models. In situations where the hardware does not support a particular peripheral or interface, functional and protocol behavior can be emulated using models and interface IP.
Two typical application cases illustrate the practical use of speed adaptors in FPGA prototyping:
Case 1: PCIe Speed Adaptor
Speed adaptors address several key challenges, including speed adaptation, protocol conversion, time decoupling, and providing controllability and observability for debugging purposes. In FPGA prototyping, the working frequency of AMD (Xilinx) PCIe PHYs ranges from 62.5 MHz for Gen1 to 500 MHz for Gen4, which is far higher than the operating frequency of synthesized user designs. When a user design is partitioned across multiple FPGA boards, the effective operating frequency can drop below 20 MHz. This creates a substantial mismatch with the PCIe PHY frequency, making reliable speed adaptation critical. The core solution for PCIe speed adaptation is the PCIe Switch IP. Its multi-port architecture allows independent link establishment and operation in different states. This enables dynamic adaptation of protocol versions, link width, and speed. The solution also integrates essential IP blocks for PCS and PIPE interface conversion, forming a complete approach for speed adaptation in PCIe systems. With this architecture, FPGA prototypes can interface with high-speed PCIe devices while maintaining functional correctness and reliable communication.
Case 2: HDMI Speed Adaptor
In this approach, HDMI audio and video streams are transmitted directly to a host system. A custom decoder extracts the video and audio data, which are then displayed using a software-based simulation of a monitor. Similar architectures are applied to DisplayPort, MIPI DSI, and USB speed adaptors. This method allows verification of a monitor. Similar architectures are applied to DisplayPort, MIPI DSI, and USB speed adaptors. This method allows verification of high-speed display and multimedia interfaces, even when the FPGA prototyping cannot operate at the full peripheral speed. It ensures that video and audio pipelines can be tested and analyzed under conditions that reflect actual system behavior.
