Xilinx 1000BASE-X - Manual (Page 56)

56 www.xilinx.com Ethernet 1000BASE-X PCS/PMA or SGMII v9.1
UG155 March 24, 2008
Chapter 5: Using the Client-side GMII Data Path R
False Carrier
Figure 5-6 illustrates the GMII signaling for a False Carrier condition. False Carrier is
asserted by the core in response to certain error conditions, such as a frame with a
corrupted start code, or for random noise.
status_vector[4:0] signals
Bit[0]: Link Status
This signal indicates the status of the link. This information is duplicated in the optional
PCS Management Registers, if present (
“Status Register (Register 1),” bit 1.2). However,
this would always serve a useful function as a Link Status LED.
When high, the link is valid: synchronization of the link has been obtained and Auto-
Negotiation (if present and enabled) has completed.
When low, a valid link has not been established. Either link synchronization has failed or
Auto-Negotiation (if present and enabled) has failed to complete.
Note: this bit is identical to the SYNC_ACQUIRED_STATUS port which was present in previous
versions of the core.
Bit[1]: Link Synchronization
This signal indicates the state of the synchronization state machine (IEEE802.3 figure 36-9).
This signal is similar to Bit[0] (Link Status), but is NOT qualified with Auto-Negotiation.
When high, link synchronization has been obtained.
When low, synchronization has failed.
Figure 5-6: False Carrier Indication
gmii_rxd[7:0]
gmii_rx_dv
gmii_rx_er
False Carrier Indication
0x0E