Micrel, Inc.
KSZ9021RL/RN
Extended Registers
Mode(1)
Address
Name
Description
Default
Register 256 (100h) – Common Control
256.15:9
256.8
Reserved
RW
RW
0000_000
0
RGMII In-band 1 = Enable
PHY Status
0 = Disable
256.7:0
Reserved
RW
Register 257 (101h) – Strap Status
257.15:6
257.5
Reserved
RO
RO
CLK125_EN
status
1 = CLK125_EN strap-in is enabled
0 = CLK125_EN strap-in is disabled
Strapped-in value for PHY Address
257.4:0
PHYAD[4:0]
status
RO
Register 258 (102h) – Operation Mode Strap Override
258.15
258.14
258.13
258.12
RGMII all
capabilities
override
1 = Override strap-in for RGMII advertise all
capabilities
RW
RW
RW
RW
RGMII no
1000BT_HD
override
1 = Override strap-in for RGMII advertise all
capabilities except 1000Base-T half-duplex
RGMII
1000BT_H/FD
only override
1 = Override strap-in for RGMII advertise
1000Base-T full and half-duplex only
RGMII
1000BT_FD
only override
1 = Override strap-in for RGMII advertise
1000Base-T full-duplex only
258.11:8
258.7
Reserved
RW
RW
Tri-state all
digital I/Os
1 = Tri-state all digital I/Os for further power
saving during software power down
0
258.6:5
258.4
Reserved
RW
RW
NAND Tree
override
1 = Override strap-in for NAND Tree mode
258.3:0
Reserved
RW
RO
Register 259 (103h) – Operation Mode Strap Status
259.15
259.14
259.13
RGMII all
capabilities
strap-in status
1 = Strap to RGMII advertise all capabilities
RGMII no
1000BT_HD
strap-in status
1 = Strap to RGMII advertise all capabilities
except 1000Base-T half-duplex
RO
RO
RGMII only
1000BT_H/FD
strap-in status
1 = Strap to RGMII advertise 1000Base-T full
and half-duplex only
259.12
RGMII only
1000BT_FD
strap-in status
1 = Strap to RGMII advertise 1000Base-T full-
duplex only
RO
RO
259.11:5
Reserved
M9999-101309-1.1
October 2009
44
MICREL [ MICREL SEMICONDUCTOR ]
