UM10503
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User manual
Rev. 1.3 — 6 July 2012
723 of 1269
NXP Semiconductors
UM10503
Chapter 26: LPC43xx Ethernet
As shown in
, the PTP uses the following process:
1. The master broadcasts the PTP Sync messages to all its nodes. The Sync message
contains the master.s reference time information. The time at which this message
leaves the master.s system is t1. This time must be captured, for Ethernet ports, at
MII.
2. The slave receives the Sync message and also captures the exact time, t2, using its
timing reference.
3. The master sends a Follow_up message to the slave, which contains t1 information
for later use.
4. The slave sends a Delay_Req message to the master, noting the exact time, t3, at
which this frame leaves the MII.
5. The master receives the message, capturing the exact time, t4, at which it enters its
system.
6. The master sends the t4 information to the slave in the Delay_Resp message.
7. The slave uses the four values of t1, t2, t3, and t4 to synchronize its local timing
reference to the master’s timing reference.
Fig 68. Networked time synchronization