Who doesn't need Ethernet timestamps?

By Alexandra Dopplinger, Freescale Semiconductor and Bill Seitz, IXXAT
Embedded.com (03/04/09, 12:00:00 AM EST)

IEEE 1588 has matured from its humble beginning in 2002 as a mechanism to synchronize Ethernet-connected test equipment into a protocol that is widely used on many of the circuit boards it was originally designed to test.

In fact, IEEE 1588 is the root of new timestamping for Industrial Ethernet protocols such as PROFINET, CIP SYNC, IEEE 802.1AS audio video bridging, the LXI consortium for the Test & Measurement industry, ITU G.8261 for telecommunications, IEC 81650 and numerous proprietary solutions which synchronize disparate Ethernet-networked clocks.

As defined by the IEEE 1588 committee, its precision time protocol (PTP) supports:

• High clock synchronization accuracy typically better than a microsecond
• Fast synchronization of networked clocks in typically fewer than 20 clock cycles
• Minimal compute and network footprint
• Synchronization of heterogeneous clocks with varying accuracy, resolution, drift and stability characteristics
• Easy configuration and operation by non-expert users for low cost and administrative setup

In July 2008, the committee released a second version (V2), which extends IEEE 1588 into larger high-performance networks. It is expected that most network systems designers will select or migrate to V2 now that it is available.

But many embedded applications already benefit from Ethernet timestamp protocols and can only be expected to proliferate further in the future with the availability of Version 2.0.

Factory and process automation applications use them it to synchronize sensors and actuators over single-wire distributed network to control automated assembly processes and time-based motion control.

Aerospace applications use them to synchronize vehicle controls. Power line management applications synchronize across large-scale distributed power grid for smooth power transfer.

Networking and telecommunications use them to lower the cost of high-precision time synchronization between communicating nodes. Professional and consumer multimedia applications are starting to use them to ensure customers don't hear or see effects of packet delay or loss from Ethernet-connected speakers and monitors.

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