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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
869 of 1441
NXP Semiconductors
UM10503
Chapter 28: LPC43xx/LPC43Sxx Ethernet
The minimum PTP clock frequency depends on the time required between two
consecutive SFD bytes. Because the MII clock frequency is fixed by IEEE specification,
the minimum PTP clock frequency required for proper operation depends upon the
operating mode and operating speed of the MAC as shown in Table 4-1.
28.7.5 IEEE 1588-2008 advanced time stamps
In addition to the basic timestamp features (see
) the ethernet controller
supports the following advanced timestamp features defined in the IEEE 1588-2008
standard:
•
Supports the IEEE 1588-2008 (version 2) time stamp format.
•
Provides an option to take snapshot of all frames or only PTP type frames.
•
Provides an option to take snapshot of only event messages.
•
Provides an option to take the snapshot based on the clock type: ordinary, boundary,
end-to-end, and peer-to-peer.
•
Provides an option to select the node to be a Master or Slave for ordinary and
boundary clock.
•
Identifies the PTP message type, version, and PTP payload in frames sent directly
over Ethernet and sends the status.
•
Provides an option to measure sub-second time in digital or binary format.
28.7.5.1 Peer-to-Peer PTP Transparent Clock (P2P TC) Message Support
The IEEE 1588-2008 version supports Peer-to-Peer PTP (Pdelay) message in addition to
SYNC, Delay Request, Follow-up, and Delay Response messages.
method to calculate the propagation delay in clocks supporting peer-to-peer path
correction.
Table 646. Minimum PTP clock frequency cycle
Mode
Minimum gap between two
SFDs
Minimum PTP frequency
100-Mbps
full-duplex
operation
168 MII clocks (128 clocks for a
64-byte frame + 24 clocks of
min IFG + 16 clocks of
preamble)
(3 * PTP) + (4 * MII)
≤
168 * MII that is,
~0.5 MHz ((168 – 4) * 40 ns ÷ 3 = 2,180 ns
period)