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TSN Aerospace Profile: Converging Real-Time Data and Control Networking in Space

The Time-Sensitive Networking (TSN) profile for aerospace, as defined in IEEE 802.1DP, provides fault-tolerant timing and assures time integrity for synchronization and timing within spacecraft networks.

Time-Sensitive Networking (TSN) is a mature and widely adopted technology in Ethernet networks, particularly across industrial, automative and telecommunicaton sectors. Its ability to deliver low and deterministic latency, time sensitivity and resiliency makes it essential for real-time traffic. If conventional Ethernet is like an undivided road, TSN introduces lane partitioning, road signs and traffic lights—dramatically improving safety and reducing travel times for data.

Spacecraft rely on robust on-board networks to interconnect flight computers, sensors, cameras and other avionics. Typically, these networks are divided into a high-speed data plane for bandwidth-intensive signals (such as video and images) and a separate control plane for low-rate but mission-critical commands and control messages. Over the years, a variety of technologies have been developed to meet the stringent requirements of space applications, including UART, SPI, I2C, SpaceWire, SpaceFibre, PCIe®, Ethernet and Time-Triggered Ethernet (TTE).

Microchip’s new PIC64-HPSC processors represent the next generation of high-performance spaceflight computing, poised to redefine the future of space computing and on-board networking. A key innovation is the integration of the TSN aerospace profile, as specified in IEEE 802.1DP, into the PIC64-HPSC’s Ethernet subsystem.

The TSN aerospace profile retains all the core benefits of TSN—such as low latency, determinism and synchronization—while introducing enhanced resiliency and fault tolerance tailored for space environments. One of the most significant advancements is the inclusion of IEEE 802.1ASed Fault-Tolerant Timing with Time Integrity. This standard enables robust, fault-tolerant timing in TSN systems by leveraging multiple time sources and distribution paths, along with advanced time integrity mechanisms. Its primary improvements include:

  • Time Agreement Generation and Preservation: Multiple time source nodes (e.g., PTP Grandmasters) collaborate to establish and maintain a unified time, even in the presence of faults or oscillator drift
  • Time Distribution: The introduction of Dependent Time and Independent Time concepts helps mitigate common-mode faults during time distribution
  • Time Selection: A time selection algorithm evaluates the skew between input times to determine the trustworthiness of each source and generate a reliable output time

Our PIC64-HPSC processors fully implement these time integrity mechanisms in compliance with the IEEE 802.1ASed standard, offering:

  • Support for time synchronization across up to four independent time domains
  • Twelve selectable timing sources per clock domain, including:
    • Multiple external sources (e.g., GNSS receivers)
    • Spacecraft’s local time
    • Multiple PTP Grandmasters
    • SpaceWire time
  • Operation as PTP Relay Instances, End Instances, and/or Grandmaster Instances
  • Simultaneous tracking four Grandmasters and recovery of four Time-of-Day (ToD) values
  • Hardware-assisted comparison of ToD values to select the most trusted source
  • Continuous monitoring of ToD skews, with detection and reporting of any time degradation
  • Support for Clock Source Time Agreement when acting as a PTP Grandmaster

IEEE 802.1AS, based on the gPTP protocol, is a cornerstone of TSN, providing precise time synchronization across network devices. The IEEE 802.1ASed extension further enhances time distribution and synchronization with improved fault tolerance and time integrity. This advancement completes the TSN aerospace profile, making TSN the natural choice for spacecraft networking.

By fully supporting the IEEE 802.1DP TSN aerospace profile—including the IEEE 802.1ASed standard—Microchip’s PIC64-HPSC processors pave the way for converged data and control networking in spacecraft, setting a new standard for reliability and performance in space missions.

For additional information:

Tao Lang, Jul 29, 2025
Tags/Keywords: Aero-Defense, Communications