User Manual#

User Manual Time Module
status: draft
security: NO
safety: QM
version: 1
realizes: wp__training_path
doc__user_manual_time
Generic Document

Overview#

This user manual provides comprehensive guidance for integrating and deploying the S-CORE time module from a system integrator perspective.

The S-CORE time module provides a robust, high-precision time base for applications on an ECU, synchronized to a network-wide PTP (Precision Time Protocol) Grandmaster Clock. The module consists of three components:

  • Client Library (score::time): C++ API for accessing synchronized time

  • TimeSlave: System daemon that synchronizes with the PTP Grandmaster over the network

  • TimeDaemon: System daemon that provides quality-assured time to client applications

This module manual covers module-level integration, deployment, and troubleshooting. For component-specific usage and configuration, refer to the component manuals below.

For build and test of the module itself, please refer to the main documentation.

Component Manuals#

For detailed component-specific user manuals:

Environment Needs#

Basic needed software environment for the module:

  • C++: C++17 or later

  • Build System: Bazel 6.0 or later

  • Operating Systems: Linux, QNX

Dependencies#

  • Standard library (STL/Core)

  • PTP Grandmaster Clock (external network time source)

  • POSIX shared memory support

  • Network hardware with PHC (PTP Hardware Clock) support

See also MODULE.bazel files for more details on dependencies.

Performance Considerations#

The time module is designed for high-performance, low-latency time access in automotive ECUs:

  • VehicleTime access: Sub-microsecond latency via POSIX shared memory with seqlock

  • Lock-free IPC: TimeDaemon reads from TimeSlave without blocking

  • Hardware clock sync: Direct PHC adjustment for nanosecond-precision synchronization

  • Minimal overhead: Singleton pattern, zero allocations in time-critical paths

For detailed performance analysis and benchmarks, this information will be added in future releases.

Integration Guidelines#

Integrating with Your Project#

  1. Add the module to your Bazel workspace:

    # In your MODULE.bazel
bazel_dep(name = "score_time", version = "1.0")

  2. Reference in your build files:

    cc_library(
    name = "my_target",
    deps = ["@score_time//score/time/vehicle_time:vehicle_time"],
)

  3. Include headers and compile your code

System Services Deployment#

The time module requires two system daemons to be running. These processes must be managed by the system’s service manager (e.g., systemd on Linux, or a launch script on QNX).

Version History, Compatibility, and Troubleshooting#

For comprehensive information on the following topics:

  • Version history and changes

  • Compatibility notes and upgrade instructions

  • Known issues and limitations

  • Troubleshooting tips and solutions

  • Security vulnerabilities (CVEs)

Safety and Security#

Safety Classification: QM (Quality Managed)

This module is designed for Quality Managed (QM) applications. For safety-critical usage requirements and guidelines, refer to the safety manual (to be added in future releases).

Security Considerations:

  • The time module assumes a trusted network for PTP communication

  • No authentication or encryption is provided for PTP messages (per IEEE 1588 standard)

  • OS-level security (Linux Capabilities) limits attack surface for TimeSlave daemon

For detailed security aspects and requirements, refer to the security manual (to be added in future releases).

License#

This module is licensed under the Apache License Version 2.0. See the LICENSE file in the repository for full license text.

Feedback and Contributions#

Your feedback and contributions are welcome! Please report issues or suggestions through the project’s issue tracker or contribute directly to the repository.