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-4 illustrates 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
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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| UG155 March 24, 2008 |