generic Precision Time Protocol (gPTP)

.. _gptp_interface:

generic Precision Time Protocol (gPTP) ######################################

.. contents:: :local: :depth: 2

Overview

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This gPTP stack supports the protocol and procedures as defined in the IEEE 802.1AS-2011 standard_ (Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks).

Supported features

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The stack handles communications and state machines defined in the IEEE 802.1AS-2011 standard_. Mandatory requirements for a full-duplex point-to-point link endpoint, as defined in Annex A of the standard, are supported.

The stack is in principle capable of handling communications on multiple network interfaces (also defined as "ports" in the standard) and thus act as a 802.1AS bridge. However, this mode of operation has not been validated on the Zephyr OS.

Supported hardware

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Although the stack itself is hardware independent, Ethernet frame timestamping support must be enabled in ethernet drivers.

Boards supported:

• :zephyr:board:frdm_k64f
• :zephyr:board:nucleo_h743zi
• :zephyr:board:nucleo_h745zi_q
• :zephyr:board:nucleo_f767zi
• :zephyr:board:sam_e70_xplained
• :zephyr:board:native_sim (only usable for simple testing, limited capabilities due to lack of hardware clock)
• :zephyr:board:qemu_x86 (emulated, limited capabilities due to lack of hardware clock)

Enabling the stack

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The following configuration option must me enabled in :file:prj.conf file.

• :kconfig:option:CONFIG_NET_GPTP

Application interfaces

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The following Application Interfaces as defined in section 9 of the standard are available:

• ClockSourceTime interface (:c:func:gptp_clk_src_time_invoke)
• ClockTargetPhaseDiscontinuity interface (:c:func:gptp_register_phase_dis_cb)
• ClockTargetEventCapture interface (:c:func:gptp_event_capture)

Testing

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The stack has been informally tested using the OpenAVnu gPTP <https://github.com/AVnu/gptp>_ and Linux ptp4l <https://linuxptp.sourceforge.net/>_ daemons. The :zephyr:code-sample:gPTP sample application <gptp> from the Zephyr source distribution can be used for testing.

.. _IEEE 802.1AS-2011 standard: https://standards.ieee.org/findstds/standard/802.1AS-2011.html

API Reference

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.. doxygengroup:: gptp