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DP83865 Datasheet(PDF) 41 Page - National Semiconductor (TI) |
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DP83865 Datasheet(HTML) 41 Page - National Semiconductor (TI) |
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41 / 86 page  41 www.national.com 3.0 Configuration (Continued) 3.2.2 Master/Slave In 1000BASE-T the two link partner devices have to be configured, one as Master and the other as Slave. The Master device by definition uses a local clock to transmit data on the wire; the Slave device uses the clock recov- ered of the incoming data from the link partner for transmit- ting its data. The Master and Slave assignments can be manually set by using strapping options or register writes. When the AN_EN pin is strapped low, strapping MULTI_EN pin low selects Slave and high selects Master mode. Reg- ister 9 bits 12:11 allows software to overwrite the strapping Master/Slave setting (Table 30). Note that if both the link partner and the local device are manually given the same Master/Slave assignment, an error will occur as indicated in 1KSTSR 0x0A bit 15. Depending on what the link partner is configured to, the manual Master/Slave mode can be resolved to eight possi- ble outcomes. Only two National PHYs will be able to link to each other in manual configuration mode. (Table 32) 3.3 Auto-Negotiation All 1000BASE-T PHYs are required to support Auto-Nego- tiation. (The 10/100 Mbps Ethernet PHYs had an option to support Auto-Negotiation, as well as parallel detecting when a link partner did not support Auto-Neg.) The Auto- Negotiation function in 1000BASE-T has three primary pur- poses: — Auto-Negotiation of Speed & Duplex Selection — Auto-Negotiation of Master/Slave Resolution — Auto-Negotiation of Pause/Asymetrical Pause Resolu- tion . The DP83865 also supports features such as: — Next Page — Parallel Detection for 10/100 Mbps — Restart Auto-Negotiation through software 3.3.1 Speed/Duplex Selection - Priority Resolution The Auto-Negotiation function provides a mechanism for exchanging configuration information between the two ends of a link segment. This mechanism is implemented by exchanging Fast Link Pulses (FLP). FLP are burst pulses that provide the signalling used to communicate the abili- ties between two devices at each end of a link segment. For further details regarding Auto-Negotiation, refer to Clause 28 of the IEEE 802.3u specification. The DP83865 supports six different Ethernet protocols: 10BASE-T Full Duplex, 10BASE-T Half Duplex, 100BASE-TX Full Duplex, 100BASE-TX Half Duplex, 1000BASE-T Full Duplex, and 1000BASE-T Half Duplex. The process of Auto-Negotiation ensures that the highest performance protocol is selected (i.e., priority resolution) based on the advertised abilities of the Link Partner and the local device. (Table 33) . Table 29. Speed/Duplex Selection, AN_EN = 0 DUPLEX SPEED[1] SPEED[0] Manual Mode 0 0 0 10BASE-T HD 0 0 1 100BASE-TX HD 0 1 0 1000BASE-T HD (Between National PHYs only) 01 1 Reserved 1 0 0 10BASE-T FD 1 0 1 100BASE-TX FD 1 1 0 1000BASE-T FD (Between National PHYs only) 11 1 Reserved Table 30. 1000BASE-T Master/Slave Sel., AN_EN = 0 MULTI_EN Manual Mode 0Slave mode 1 Master mode Table 31. Master/Slave Resolution, AN_EN = 0 DP83865 Advertise Link Partner Advertise DP83865 Outcome Link Partner Outcome Manual Master Manual Master Unresolved No Link Unresolved No Link Manual Master Manual Slave Master Slave Manual Master Multi-node (Auto-neg) Master Slave Manual Master Single-node (Auto-neg) Master Slave Manual Slave Manual Master Slave Master Manual Slave Manual Slave Unresolved No Link Unresolved No Link Manual Slave Multi-node (Auto-neg) Slave Master Manual Slave Single-node (Auto-neg) Slave Master Table 32. Master/Slave Resolution, AN_EN = 0 DP83865 Advertise Link Partner Advertise DP83865 Outcome Link Partner Outcome Manual Master Manual Master Unresolved No Link Unresolved No Link Manual Master Manual Slave Master Slave Manual Master Multi-node (Auto-neg) Master Slave Manual Master Single-node (Auto-neg) Master Slave Manual Slave Manual Master Slave Master Manual Slave Manual Slave Unresolved No Link Unresolved No Link Manual Slave Multi-node (Auto-neg) Slave Master Manual Slave Single-node (Auto-neg) Slave Master |
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