DP83849IFVSSLASHNOPB datasheet(44/108 Pages) TI2

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DP83849IF

SNOSAX8D – JUNE 2009 – REVISED APRIL 2013

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6.5.3

Common Flexible MII Port Configurations

Table 6-7. Common Flexible MII Port Configurations

Channel A

Channel B

Mode

Description

RBR[12:9]

Normal

0000

MII port A assigned to Channel A,

MII Port B assigned to Channel B

Full Port Swap

0101

MII port A assigned to Channel B,

MII Port B assigned to Channel A

Extender/Media Converter

1110

MII RX disabled, Channel A transmits from Channel B RX data,

Channel B transmits from Channel A RX data

Broadcast TX MII Port A

xx00

xx01

Both Channels transmit from TX MII Port A

Broadcast TX MII Port B

xx01

xx00

Both Channels transmit from TX MII Port B

Mirror RX Channel A

10xx

11xx

Channel A RX traffic appears on both Ports

Mirror RX Channel B

11xx

10xx

Channel B RX traffic appears on both Ports

Disable Port A

1111

xxxx

MII Port A is disabled

Disable Port B

xxxx

1111

MII Port B is disabled

6.5.4

Strapped Extender or Media Converter Mode

The DP83849IF provides a simple strap option to automatically configure both channels for Extender or

Media Converter Mode with no device register configuration necessary. The EXTENDER_EN Strap can

be used in conjunction with the Auto-Negotiation Straps (AN_EN, AN0, AN1), the RMII Mode Strap, and

the Fiber Mode (FX_EN) Strap to allow many possible configurations. If Extender Mode is strapped but

RMII Mode is not, both channels will automatically be configured for Single Clock MII Receive and

Transmit Modes. The optional use of RMII Mode in conjunction with Extender Mode allows flexibility in the

system design.

Several common configurations are shown in Table 6-8.

Table 6-8. Common Strapped Extender/Media Converter Mode Configurations

Mode

Auto-Negotiation Straps

Fiber Mode Straps

100Mb Copper Extender

Both channels are forced to 100Mb Full Duplex

Disabled for both channels

100Mb Fiber Extender

N/A

Enabled for both channels

10Mb Copper Extender

Both channels are forced to 10Mb Full Duplex

Disabled for both channels

100Mb Media Converter

One channel is forced to 100Mb Full Duplex

Enabled for the other channel

6.5.5

Notes and Restrictions

•

Extender/Media Converter: Both channels must be operating at the same speed (10 or 100Mb). This

can be accomplished using straps or channel register controls. Both channels must be in Full Duplex

mode. Both channels must either be in RMII Mode (RBR:RMII_EN = 1) or full Single Clock MII Mode

(RBR:SCMII_RX = 1 and RBR:SCMII_TX = 1) to ensure synchronous operation. If only one RX to TX

path is enabled, SCMII_RX in the RX channel (RBR register 17h bit 7) and SCMII_TX in the TX

channel (RBR register 17h bit 6) must be set to 1. Media Conversion is only supported in 100Mb

mode; one channel must be in Fiber Mode (100Base-FX) and the other channel must be in Copper

Mode (100Base-TX).

•

Broadcast TX MII Port Mode: To ensure synchronous operation, both channels must be in RMII

Mode (RBR register 17h bit 5 = 1) or in Single Clock TX MII Mode (RBR register 17h bit 6 = 1). Both

channels must be operating at the same speed (10 or 100Mb). Both channels must be in Full Duplex

mode to ensure no collisions are seen. This is because in Single Clock TX MII Mode, a collision on

one PHY channel would cause both channels to send the Jam pattern.

MAC Interface

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