146 www.xilinx.com Ethernet 1000BASE-X PCS/PMA or SGMII v9.1
UG155 March 24, 2008
Chapter 9: Configuration and Status
R
Table 9-30: SGMII Control (Register 0)
Bit(s) Name Description Attributes
Default
Value
0.15 Reset 1 = Core Reset
0 = Normal Operation
read/write
self clearing
0
0.14 Loopback 1 = Enable Loopback Mode
0 = Disable Loopback Mode
When used with a RocketIO
transceiver, the core is placed in
internal loopback mode.
With the TBI version, Bit 1 is
connected to ewrap. When set to ‘1’
indicates to the external PMA
module to enter loopback mode.
See “Loopback,” page 197.
read/write 0
0.13 Speed
Selection
(LSB)
Always returns a ‘0’ for this bit.
Together with bit 0.6, speed selection
of 1000 Mbps is identified
returns 0 0
0.12 Auto-
Negotiation
Enable
1 = Enable SGMII Auto-Negotiation
Process
0 = Disable SGMII Auto-Negotiation
Process
read/write 1
0.11 Power Down 1 = Power down
0 = Normal operation
With the PMA option, when set to ’1’
the RocketIO transceiver is placed in
a low-power state. This bit requires a
reset (see bit 0.15) to clear.
With the TBI version this register bit
has no effect.
read/ write 0
0.10 Isolate 1 = Electrically Isolate SGMII logic
from GMII
0 = Normal operation
read/write 1
0.9 Restart Auto-
Negotiation
1 = Restart Auto-Negotiation
Process across SGMII link
0 = Normal Operation
read/write
self clearing
0
0.8 Duplex Mode Always returns a ‘1’ for this bit to
signal Full-Duplex Mode
returns 1 1
0.7 Collision Test Always returns a ‘0’ for this bit to
disable COL test
returns 0 0
0.6 Speed
Selection
(MSB)
Always returns a ‘1’ for this bit.
Together with bit 0.13, speed
selection of 1000 Mbps is identified
returns 1 1
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