R

Appendix D: 1000BASE-X State Machines

gmii_txd[7:0]

preamble

gmii_tx_en

gmii_tx_er

SFD

PCS Transmit Engine Encoding

tx_code_group I2 I2 I2 S preamble

SFD

Figure D-3:1000BASE-X Transmit State Machine Operation (Odd Case)

Reception of the Odd Case

Figure D-4illustrates the reception of the in-bound code-group stream, received either 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 Figure D-3) frame (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.

rx_code_group I2 I2 I2 S preamble

SFD

PCS Receive Engine Decoding

gmii_rxd[7:0]preamble

gmii_rx_dv

gmii_rx_er

SFD

Figure D-4:1000BASE-X Reception State Machine Operation (Odd Case)

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Ethernet 1000BASE-X PCS/PMA or SGMII v9.1

 

 

UG155 March 24, 2008

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Xilinx 1000BASE-X manual Reception of the Odd Case