KSZ9031RNX(2012) Ver la hoja de datos (PDF) - Micrel

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Fabricante

KSZ9031RNX
(Rev.:2012)

Gigabit Ethernet Transceiver with RGMII Support

Micrel 

Micrel, Inc.

KSZ9031RNX

Figure 3. Auto-Negotiation Flow Chart

For 1000Base-T mode, auto-negotiation is always required to establish a link. During 1000Base-T auto-negotiation, the

master and slave configuration is first resolved between link partners. Then the link is established with the highest

common capabilities between link partners.

Auto-negotiation is enabled by default after power-up or hardware reset. After that, auto-negotiation can be enabled or

disabled through register 0h, bit [12]. If auto-negotiation is disabled, the speed is set by register 0h, bits [6, 13] and the

duplex is set by register 0h, bit [8].

If the speed is changed on the fly, the link goes down and auto-negotiation and parallel detection initiate until a common

speed between KSZ9031RNX and its link partner is re-established for a link.

If the link is already established and there is no change of speed on the fly, the changes (for example, duplex and pause

capabilities) will not take effect unless either auto-negotiation is restarted through register 0h, bit [9], or a link-down to link-

up transition occurs (that is, disconnecting and reconnecting the cable).

After auto-negotiation is completed, the link status is updated in register 1h, bit [2], and the link partner capabilities are

updated in registers 5h, 6h, 8h, and Ah.

The auto-negotiation finite state machines use interval timers to manage the auto-negotiation process. The duration of

these timers under normal operating conditions is summarized in Table 2.

October 2012

21

M9999-103112-1.0

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