Datasheet

Micrel, Inc. KS8721BL/SL
June 2009
19
M9999-062509-1.3
Register Map
Register No. Description
0h Basic Control Register
1h Basic Status Register
2h PHY Identifier I
3h PHY Identifier II
4h Auto-Negotiation Advertisement Register
5h Auto-Negotiation Link Partner Ability Register
6h Auto-Negotiation Expansion Register
7h Auto-Negotiation Next Page Register
8h Link Partner Next Page Ability
15h RXER Counter Register
1bh Interrupt Control/Status Register
1fh 100BASE-TX PHY Control Register
Address Name Description Default
(1)
Mode
Register 0h - Basic Control
0.15 Reset 1 = software reset. Bit is self-clearing RW/SC 0
0.14 Loop-Back
1 = loop-back mode
0 = normal operation
RW 0
0.13 Speed Select (LSB)
1 = 100Mbps
0 = 10Mbps
Ignored if Auto-Negotiation is enabled (0.12 = 1)
RW
Set by
SPD100
0.12 Auto-Negotiation Enable
1 = enable auto-negotiation process (override 0.13 and 0.8)
0 = disable auto-negotiation process
RW
Set by
NWAYEN
0.11 Power Down
1 = power-down mode
0 = normal operation
RW 0
0.10 Isolate
1 = electrical isolation of PHY from MII and TX+/TX-
0 = normal operation
RW Set by ISO
0.9 Restart Auto-Negotiation
1 = restart auto-negotiation process
0 = normal operation. Bit is self-clearing
RW/SC 0
0.8 Duplex Mode
1 = full-duplex
0 = half-duplex
RW
Set by
DUPLEX
0.7 Collision Test
1 = enable COL test
0 = disable COL test
RW 0
0.6:1 Reserved RO 0
0.0
Disable
Transmitter
0 = enable transmitter
1 = disable transmitter
RW 0
Register 1h - Basic Status
1.15 100BASE-T4
1 = T4 capable
0 = not T4 capable
RO 0
1.14 100BASE-TX Full-Duplex
1 = capable of 100BASE-X full-duplex
0 = not capable of 100BASE-X full-duplex
RO 1