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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
876 of 1441
NXP Semiconductors
UM10503
Chapter 28: LPC43xx/LPC43Sxx Ethernet
[1]
The address match of destination addresses (DA) programmed in MAC address 1 to 31 is used if the
control bit 18 (TSENMACADDR: Enable MAC address for PTP frame filtering) of the Timestamp Control
register is set.
[2]
IEEE standard 1588-2008, Annex F
[3]
The Ethernet controller does not consider the PTP version 1 messages with Peer delay multicast address
(01-80-C2-00-00- 0E) as valid PTP messages.
28.7.5.4 Reference timing source
The ethernet controller supports the 48-bit seconds field reference timing sources
featured in the IEEE 1588-2008 standard.
28.7.5.4.1
48-bit seconds field
The ethernet controller supports 80-bit timestamping. The timestamp has the following
fields:
•
UInteger48 secondsField
The seconds field is the integer portion of the timestamp in units of seconds and is
48-bits wide. For example, 2.000000001 seconds are represented as secondsField =
0x0000_0000_0002.
•
UInteger32 nanosecondsField
The nanoseconds field is the fractional portion of the timestamp in units of
nanoseconds. For example, 2.000000001 nanoseconds are represented as
nanoSeconds = 0x0000_0001.
The nanoseconds field supports the following two modes:
–
Digital rollover mode: In digital rollover mode, the maximum value in the
nanoseconds field is 0x3B9A_C9FF, that is, (10e9-1) nanoseconds.
–
Binary rollover mode: In binary rollover mode, the nanoseconds field rolls over and
increments the seconds field after value 0x7FFF_FFFF. Accuracy is ~0.466 ns per
bit.
You can set these modes by using the bit 9 (TSCTRLSSR) of
.
When you select the advanced timestamp feature, the timestamp maintained in the core is
still 64-bit wide. The overflow to the upper 16-bits of seconds register happens once in
130 years. You can read the values of the upper 16-bits of the seconds field from the CSR
register.
28.7.5.5 Transmit path functions
There is no change in the transmit path functions for the Advanced timestamp feature.
The structure of the descriptor changes when you enable the advanced timestamp
feature. The advanced timestamp feature is supported only through Alternate (Enhanced)
descriptors format. The descriptor is 32-bytes long (8 DWORDS) and the snapshot of the
timestamp is written in descriptor TDES6 and TDES7. For detailed information about
descriptors, see
.