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,
when setting this bit do not set other bits in this
register. The configuration (as described in
Section 5.3.9.2) is set from the register bit values,
and not from the mode pins.
RW/
SC
0
0.14
0.13
Loopback
1 = loopback mode,
0 = normal operation
RW
RW
0
Speed Select
1 = 100Mbps,
0 = 10Mbps.
Ignored if Auto Negotiation is enabled (0.12 = 1).
Set by
MODE[2:0]
bus
0.12
Auto-
Negotiation
Enable
1 = enable auto-negotiate process
(overrides 0.13 and 0.8)
0 = disable auto-negotiate process
RW
Set by
MODE[2:0]
bus
0.11
0.10
0.9
Power Down
1 = General power down mode,
0 = normal operation
RW
RW
0
0
0
Isolate
1 = electrical isolation of transceiver from MII
0 = normal operation
Restart Auto-
Negotiate
1 = restart auto-negotiate process
0 = normal operation. Bit is self-clearing.
RW/
SC
0.8
Duplex Mode
1 = Full duplex,
RW
Set by
MODE[2:0]
bus
0 = Half duplex.
Ignored if Auto Negotiation is enabled (0.12 = 1).
0.7
Collision Test
Reserved
1 = enable COL test,
0 = disable COL test
RW
RO
0
0.6:0
0
Table 5.22 Register 1 - Basic Status
DESCRIPTION
ADDRESS
NAME
MODE
DEFAULT
1.15
100Base-T4
1 = T4 able,
0 = no T4 ability
RO
0
1.14
1.13
1.12
1.11
100Base-TX Full
Duplex
1 = TX with full duplex,
RO
RO
RO
RO
1
1
1
1
0 = no TX full duplex ability
100Base-TX Half
Duplex
1 = TX with half duplex,
0 = no TX half duplex ability
10Base-T Full
Duplex
1 = 10Mbps with full duplex
0 = no 10Mbps with full duplex ability
10Base-T Half
Duplex
1 = 10Mbps with half duplex
0 = no 10Mbps with half duplex ability
1.10:6
1.5
Reserved
Auto-Negotiate
Complete
1 = auto-negotiate process completed
0 = auto-negotiate process not completed
RO
0
SMSC LAN8720/LAN8720i
Revision 1.0 (05-28-09)
DATA4S1HEET
SMSC [ SMSC CORPORATION ]
