
R
Chapter 5: Using the Client-side GMII Data Path
be included in the frame supplied to the core. The RocketIO transceiver will replace these four bytes with the calculated CRC value.
gmii_txd[7:0]preamble
gmii_tx_en
gmii_tx_er
SFD
4 place holder bytes
Figure 5-8: GMII Frame Transmission with RocketIO Transceiver CRC Logic
Enabled
GMII Reception
The timing of normal inbound frame transfer with RocketIO transceiver CRC functionality is illustrated in Figure
Please note that RXCHECKINGCRC and RXCRCERR are obtained directly from the output of the RocketIO transceiver. The core receiver behavior is unchanged.
preamble | SFD | FCS |
gmii_rxd[7:0] |
| |
|
| |
gmii_rx_dv |
|
|
gmii_rx_er |
|
|
RXCHECKINGCRC |
|
|
RXCRCERR |
|
|
3 clock periods
Figure 5-9: GMII Frame Reception with the RocketIO Transceiver CRC Logic
Enabled
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