Ethernet 1000BASE-X PCS/PMA or SGMII v9.1
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UG155 March 24, 2008
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Appendix F
Debugging Guide
This appendix provides assistance for debugging the core within a system. For additional
help, contact Xilinx by submitting a WebCase at
support.xilinx.com/
.
General Checks
•
Ensure that all the timing constraints for the core were met during Place and Route.
•
Does it work in timing simulation? If problems are seen in hardware but not in timing
simulation, this could indicate a PCB issue.
•
Ensure that all clock sources are clean. If using DCMs in the design, ensure that all
DCMs have obtained lock by monitoring the
LOCKED
port.
Problems with the MDIO
•
Ensure that the MDIO is driven properly. See
“MDIO Management Interface,” page
115
for detailed information about performing MDIO transactions.
•
Check that the
mdc
clock is running and that the frequency is 2.5 MHz or less.
•
Read from a configuration register that does not have all 0s as a default. If all 0s are
read back, the read was unsuccessful. Check that the PHYAD field placed into the
MDIO frame matches the value placed on the
phyad[4:0]
port of the core.
Problems with Data Reception or Transmission
When no data is being received or transmitted:
•
Ensure that a valid link has been established between the core and its link partner,
either by Auto-Negotiation or Manual Configuration:
status_vector[0]
and
status_vector[1]
should both be high. If no link has been established, see the
topics discussed in the next section.
♦
“Problems with Auto-Negotiation”
♦
“Problems in Obtaining a Link (Auto-Negotiation Disabled)”
Note:
Transmission through the core is not allowed unless a link has been established. This
behavior can be overridden by setting the Unidirectional Enable bit.
•
Ensure that the Isolate state has been disabled.
By default, the Isolate state is enabled after power-up. For an external GMII, the PHY
will be electrically isolated from the GMII; for an internal GMII, it will behave as if it is
isolated. This results in no data transfer across the GMII. See
“Startup Sequencing,”
page 197
for more information.
