Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
4.2.1
Basic Control Register
Index (In Decimal):
0
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15
Soft Reset
R/W
SC
0b
1 = software reset. Bit is self-clearing. When setting this bit do not set other
bits in this register. The configuration (as described in Section 3.7.2,
"MODE[2:0]: Mode Configuration," on page 31) is set from the register bit
values, and not from the mode pins.
14
13
Loopback
R/W
R/W
0b
0 = normal operation
1 = loopback mode
Speed Select
0 = 10Mbps
1 = 100Mbps
Note 4.1
Note:
Ignored if Auto-negotiation is enabled (0.12 = 1).
12
11
Auto-Negotiation Enable
R/W
R/W
Note 4.1
0b
0 = disable auto-negotiate process
1 = enable auto-negotiate process (overrides 0.13 and 0.8)
Power Down
0 = normal operation
1 = General power down mode
Note:
The Auto-Negotiation Enable must be cleared before setting the
Power Down.
10
9
Isolate
R/W
0b
0b
0 = normal operation
1 = electrical isolation of PHY from the RMII
Restart Auto-Negotiate
0 = normal operation
1 = restart auto-negotiate process
R/W
SC
Note:
Bit is self-clearing.
8
Duplex Mode
0 = half duplex
1 = full duplex
R/W
RO
Note 4.1
Note:
Ignored if Auto-Negotiation is enabled (0.12 = 1).
7:0
RESERVED
-
Note 4.1 The default value of this bit is determined by the MODE[2:0] configuration straps. Refer to
Section 3.7.2, "MODE[2:0]: Mode Configuration," on page 31 for additional information.
SMSC LAN8720A/LAN8720Ai
49
Revision 1.4 (08-23-12)
DATASHEET
SMSC [ SMSC CORPORATION ]
