PCIe and Ethernet co-exist as essential interfaces for the automotive data backbone. Presently, PCIe is mostly contained to intra-ECU processor connections only, whereas high-speed inter-ECU connectivity over automotive cabling is predominantly enabled by automotive Ethernet. Automotive Ethernet serves well as an ideal inter-ECU interface due to the creation of NBASE-T1 standards for full duplex signaling of TX and RX over a single differential pair. With the ratification of the Multigig Ethernet standard IEEE802.3ch in 2020, Ethernet bandwidth further increases to support up to 10 Gbps (10GBASE-T1) over a single shielded twisted pair (STP) cable up to 15 m. With a minimal cabling interface, OEMs have used automotive Ethernet to reduce overall cable count significantly and optimize fuel economy due to reduced cable weight. For high-bandwidth inter-ECU cabling applications where minimal cable count is prioritized over real-time processing and maximized TOPS, automotive Ethernet will continue to provide numerous benefits as a high-speed interface.

As the automotive industry trends towards shared processing and redundancy across the data backbone, transporting native PCIe end-to-end beyond the PCB becomes increasingly attractive in comparison to the traditional method of converting PCIe via NIC to Ethernet for cabling interconnect and then converting back to PCIe at the destination ECU. By converting one interface technology to another, the inherent benefits of PCIe are lost. Instead, processors connected end-to-end by native PCIe can exploit the benefits of the protocol’s ultra-low latency, guaranteed reliability, and DMA that are critical for maximizing computational efficiency and optimizing real-time processing performance. For high-bandwidth inter-ECU cabling applications where both real-time processing and maximized TOPS are prioritized over cable count, PCIe emerges as a worthy and valid high-speed complement to automotive Ethernet.