NXP Semiconductors LPC43 Series User Manual

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NXP Semiconductors LPC43 Series User Manual Manual pdf 728 page image

UM10503 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.User manual Rev. 1.3 — 6 July 2012 728 of 1269NXP Semiconductors UM10503Chapter 26: LPC43xx EthernetThe minimum PTP clock frequency depends on the time required between twoconsecutive SFD bytes. Because the MII clock frequency is fixed by IEEE specification,the minimum PTP clock frequency required for proper operation depends upon theoperating mode and operating speed of the MAC as shown in Table 4-1.26.7.4 IEEE 1588-2008 advanced timestampsIn addition to the basic timestamp features (see Section 26.7.3) the ethernet controllersupports the following advanced timestamp features defined in the IEEE 1588-2008standard:• Supports the IEEE 1588-2008 (version 2) timestamp 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 andboundary clock.• Identifies the PTP message type, version, and PTP payload in frames sent directlyover Ethernet and sends the status.• Provides an option to measure sub-second time in digital or binary format.26.7.4.1 Peer-to-Peer PTP Transparent Clock (P2P TC) Message SupportThe IEEE 1588-2008 version supports Peer-to-Peer PTP (Pdelay) message in addition toSYNC, Delay Request, Follow-up, and Delay Response messages. Figure 70 shows themethod to calculate the propagation delay in clocks supporting peer-to-peer pathcorrection.Table 576. Minimum PTP clock frequency cycleMode Minimum gap between twoSFDsMinimum PTP frequency100-Mbpsfull-duplexoperation168 MII clocks (128 clocks for a64-byte frame + 24 clocks ofmin IFG + 16 clocks ofpreamble)(3 * PTP) + (4 * MII) ≤ 168 * MII that is,~0.5 MHz ((168 – 4) * 40 ns ÷ 3 = 2,180 nsperiod)