Reception of the Odd Case - 16.2 English

1G/2.5G Ethernet PCS/PMA or SGMII LogiCORE IP Product Guide (PG047)

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16.2 English
The following figure shows the reception of the in-bound code-group stream, received either serially using the device-specific 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.

As defined in IEEE 802.3-2008 figure 36-7b, the combined /T/R/R/ sequence results in the GMII encoding of Frame Extension. This occurs for a single clock cycle following the end of frame reception; the gmii_rx_er signal is driven High and the frame extension code of 0x0F is driven onto gmii_rxd[7:0]. This occurs even in full-duplex mode.

Figure 1. 1000BASE-X Reception State Machine Operation (Odd Case) gmii_rxd[7:0] gmii_rx_dv gmii_rx_er FCS rx_code_g roup FCS I2 I2 I2 T R I1/I2 R 0x0F PCS Receiv e Engine Decoding X12853