Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support

Datasheet

Table 5.21 Register 0 - Basic Control
ADDRESS

NAME

 

DESCRIPTION

MODE

DEFAULT

 

 

 

 

 

0.15

Reset

1 = software reset. Bit is self-clearing. For best results,

RW/

0

 

 

 

when setting this bit do not set other bits in this

SC

 

 

 

 

register. The configuration (as described in

 

 

 

 

 

Section 5.3.9.2) is set from the register bit values,

 

 

 

 

 

and not from the mode pins.

 

 

 

 

 

 

 

 

0.14

Loopback

1

= loopback mode,

RW

0

 

 

0

= normal operation

 

 

 

 

 

 

 

 

0.13

Speed Select

1

= 100Mbps,

RW

Set by

 

 

0

= 10Mbps.

 

MODE[2:0]

 

 

Ignored if Auto Negotiation is enabled (0.12 = 1).

 

bus

 

 

 

 

 

 

0.12

Auto-

1

= enable auto-negotiate process

RW

Set by

 

Negotiation

 

(overrides 0.13 and 0.8)

 

MODE[2:0]

 

Enable

0

= disable auto-negotiate process

 

bus

 

 

 

 

 

 

0.11

Power Down

1

= General power down mode,

RW

0

 

 

0

= normal operation

 

 

 

 

 

 

 

 

0.10

Isolate

1

= electrical isolation of transceiver from MII

RW

0

 

 

0

= normal operation

 

 

 

 

 

 

 

 

0.9

Restart Auto-

1

= restart auto-negotiate process

RW/

0

 

Negotiate

0

= normal operation. Bit is self-clearing.

SC

 

 

 

 

 

 

 

0.8

Duplex Mode

1

= Full duplex,

RW

Set by

 

 

0

= Half duplex.

 

MODE[2:0]

 

 

Ignored if Auto Negotiation is enabled (0.12 = 1).

 

bus

 

 

 

 

 

 

0.7

Collision Test

1

= enable COL test,

RW

0

 

 

0

= disable COL test

 

 

 

 

 

 

 

 

0.6:0

Reserved

 

 

RO

0

 

 

 

 

 

 

Table 5.22 Register 1 - Basic Status

ADDRESS

NAME

 

DESCRIPTION

MODE

DEFAULT

 

 

 

 

 

1.15

100Base-T4

1 = T4 able,

RO

0

 

 

0

= no T4 ability

 

 

 

 

 

 

 

 

1.14

100Base-TX Full

1

= TX with full duplex,

RO

1

 

Duplex

0

= no TX full duplex ability

 

 

 

 

 

 

 

 

1.13

100Base-TX Half

1

= TX with half duplex,

RO

1

 

Duplex

0

= no TX half duplex ability

 

 

 

 

 

 

 

 

1.12

10Base-T Full

1

= 10Mbps with full duplex

RO

1

 

Duplex

0

= no 10Mbps with full duplex ability

 

 

 

 

 

 

 

 

1.11

10Base-T Half

1

= 10Mbps with half duplex

RO

1

 

Duplex

0

= no 10Mbps with half duplex ability

 

 

 

 

 

 

 

 

1.10:6

Reserved

 

 

 

 

 

 

 

 

 

 

1.5

Auto-Negotiate

1

= auto-negotiate process completed

RO

0

 

Complete

0

= auto-negotiate process not completed

 

 

 

 

 

 

 

 

SMSC LAN8720/LAN8720i

41

Revision 1.0 (05-28-09)

 

DATASHEET