AUTOSAR tsync

tsync — Time Synchronization

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What ARA defines

ara::tsync provides a common, synchronized notion of time across the platform — time bases disciplined from a grandmaster (PTP/gPTP over automotive Ethernet, or GNSS) so that distributed ECUs agree on timestamps for fusion, logging, and scheduling. Applications read a time base; the FC owns the disciplining.

Our adaptation

Theia's tsync is a thin control plane over Linux PTP + a custom in-process GPS driver — deliberately not a stack of external daemons.

• No gpsd / chronyd / NTP. The GNSS time source is a custom in-process driver behind a gps_backend.hpp seam with bazel-selectable variants — gps_fake (default, for dev/CI), gps_nmea ($GxRMC/$GxGGA), gps_rtk (UBX-NAV-PVT, ZED-F9R). --define gps=rtk|nmea.
• PTP is the network time base; the disciplining-the-system-clock path (clock_settime / PPS) is gated and is the remaining hardware-rig follow-up.
• TimeSource enum is SYSTEM / PTP / GPS — NTP was dropped as a non-fit for the embedded target.

Practicality over spec: ARA assumes a richer time-base hierarchy; we ship the two sources that matter for our rigs (PTP slave, GNSS) and keep the rest a seam to fill when a board needs it.