LXT975B datasheet(64/74 Pages) INTEL

64 / 74 page

LXT974/LXT975 — Fast Ethernet 10/100 Quad Transceivers

Datasheet

Table 44. Control Register

Bit

Name

Description

Type 1

Default

0.15

Reset

1 = Reset port.

0 = Enable normal operation.

R/W

0.14

Loopback

1 = Enable loopback mode.

0 = Disable loopback mode.

R/W

0.13

Speed

Selection

1 = 100 Mbps.

0 = 10 Mbps.

R/W

Note 2

0.12

Auto-Negotiation

Enable

1 = Enable auto-negotiate process (overrides speed select and

duplex mode bits).

0 = Disable auto-negotiate process.

R/W

Note 3

0.11

Power Down

1 = Enable power down.

0 = Enable normal operation.

R/W

Note 4

0.10

Isolate

1 = Electrically isolate port from MII.

0 = Normal operation.

R/W

Note 5

0.9

Restart Auto-

Negotiation

1 = Restart auto-negotiation process.

0 = Normal operation.

R/W

Note 6

0.8

Duplex Mode

1 = Enable full-duplex.

0 = Enable half-duplex.

R/W

Note 7

0.7

Collision Test

1 = Enable COL signal test.

0 = Disable COL signal test.

R/W

Note 8

0.6:4

Transceiver Test

Mode

Not supported.

0.3

Master-Slave

Enable

Not supported.

0.2

Master-Slave Value

Not supported.

0.1:0

Reserved

Write as 0; ignore on read.

R/W

N/A

1. R/W = Read/Write

RO = Read Only

SC = Self Clearing

2. If auto-negotiation is enabled, this bit is ignored. If auto-negotiation is disabled, the default value of bit 0.13 is determined by

CFG_0.

3. If SD_TXn is tied High or to a 5V PECL input (FX Mode), the default value of bit 0.12 = 0. If SD_TXn is tied Low (TP Mode),

the default value of bit 0.12 is determined by AUTOENA.

4. The LXT974/975 internally holds all set values of the configuration registers upon exiting power down mode. A delay of 500

ns minimum is required from the time power down is cleared until any register can be written.

5. The default value of bit 0.10 is determined by pin TRSTEn.

6. If auto-negotiation is enabled, the default value of bit 0.9 is determined by CFG_0.

If auto-negotiation is disabled, the bit is ignored.

7. If auto-negotiation is enabled, this bit is ignored. If auto-negotiation is disabled and the port is operating in TX mode, the

default value of bit 0.8 is determined by pin FDE. If auto-negotiation is disabled and the port is operating in FX mode, the

default value of bit 0.8 is determined by pin FDE_FX.

8. This bit is ignored unless loopback is enabled (bit 0.14 = 1).

LXT975B Datasheet(PDF) 64 Page - Intel Corporation

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