Ethernet-SpaceWire Bridge for Spacecraft Data Routing
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Solution Overview
Problem
Commercial SOC processors lack direct support for SpaceWire interfaces required for space applications, leading to high complexity and lower-than-required performance due to the lack of radiation-tolerant PHY devices and added cost, complexity, and power consumption.
Innovation Solution
A system comprising an Ethernet media access controller (MAC) and a bridge device with a SpaceWire physical interface and FIFO buffers that segment and reassemble data packets to enable direct connection of SpaceWire interfaces to existing SOC point-to-point Ethernet MAC interfaces, avoiding the need for PHY devices and reducing design complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If commercial SOC processors are used without direct SpaceWire support, then cost and complexity are reduced, but performance and reliability deteriorate due to lack of radiation tolerance and interface compatibility
Solution Approach 1:
The patent introduces a bridge device as an intermediary component between the commercial SOC processor and the SpaceWire network. This bridge device includes a SpaceWire physical interface layer (PHY) that handles radiation-tolerant SpaceWire signaling, while the SOC processor uses standard Ethernet MAC interfaces. The bridge performs protocol conversion and packet segmentation/reassembly, enabling the SOC to communicate with SpaceWire devices without requiring radiation-hardened processors, thus resolving the contradiction between using commercial off-the-shelf components and maintaining space-grade reliability.
2Productivity
If dedicated point-to-point I/O interfaces are used for SpaceWire connectivity, then performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the Ethernet MAC interface universal by enabling it to handle SpaceWire traffic through the bridge device. The Ethernet MAC, originally designed for standard Ethernet protocols, is repurposed to carry SpaceWire packets by segmenting and reassembling data at the bridge layer. This allows a single Ethernet MAC interface to serve dual purposes: standard Ethernet communication and SpaceWire network access, thereby improving productivity without proportionally increasing device complexity.
Solution Approach 2:
The bridge device segments SpaceWire packets into smaller Ethernet-compatible frames for transmission over the Ethernet MAC interface. This segmentation allows large SpaceWire data packets to be broken into manageable chunks that fit Ethernet frame size limitations, enabling high-throughput SpaceWire communication through standard Ethernet infrastructure without requiring specialized high-speed interfaces in the SOC processor.
3Device complexity
If shared parallel bus is used for onboard data communication, then device complexity is reduced, but throughput and latency performance deteriorate
Solution Approach 1:
The bridge device acts as an intermediary that translates between the shared parallel bus architecture and the point-to-point Ethernet MAC interfaces. By placing the bridge between the SOC processor and SpaceWire devices, it enables dedicated communication paths through Ethernet MACs while the shared bus remains simple. The bridge handles protocol conversion and packet management, allowing multiple SpaceWire interfaces to operate concurrently without contending for shared bus bandwidth, thus improving throughput while maintaining simple bus architecture.
Data Source
AI summary
A system for interfacing Ethernet with SpaceWire comprises a processor including an Ethernet MAC, and a bridge device connected between the processor and a SpaceWire subsystem or network. The bridge device comprises a SpaceWire physical interface that receives SpaceWire data packets, and an Ethernet MAC packet builder that includes digital logic for segmentation of the data packets into Ethernet compatible packet segments. An Ethernet media independent interface receives the packet segments from the packet builder and outputs the packet segments to the Ethernet MAC. The Ethernet media independent interface also receives Ethernet data packets transmitted from the Ethernet MAC. An Ethernet MAC packet extractor receives the Ethernet data packets from the Ethernet media independent interface and includes digital logic for performing reassembly of the Ethernet data packets into SpaceWire compatible data packets, which are sent to the SpaceWire physical interface for transmission to the SpaceWire subsystem or network.