Reception Of The Odd Case - Xilinx LogiCORE 1000BASE-X User Manual

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Reception of the Odd Case

Figure D-4
serially using the RocketIO transceiver, or in parallel across the TBI, and translation of this
code-group stream into the receiver GMII. This is performed by the PCS Receive Engine.
Note that the Start of Packet code group /S/ is again replaced with a preamble byte.
However, the first preamble byte of the original transmit GMII (see
(which was replaced with the /D16.2/ character to complete the Idle sequence), has not
been replaced. This has resulted in a single byte of preamble loss across the system.
214
gmii_txd[7:0]
gmii_tx_en
gmii_tx_er
tx_code_group
I2 I2
Figure D-3: 1000BASE-X Transmit State Machine Operation (Odd Case)
illustrates the reception of the in-bound code-group stream, received either
rx_code_group I2
I2
gmii_rxd[7:0]
gmii_rx_dv
gmii_rx_er
Figure D-4: 1000BASE-X Reception State Machine Operation (Odd Case)
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Appendix D: 1000BASE-X State Machines
preamble
S
I2 preamble
S
I2 preamble
preamble
Ethernet 1000BASE-X PCS/PMA or SGMII v9.1
PCS Transmit Engine Encoding
Figure D-3) frame
PCS Receive Engine Decoding
UG155 March 24, 2008