Xilinx Virtex-4 User Manual
Also see for Virtex-4 RocketIO: User guideConfiguration user guide
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Embedded Tri-Mode Ethernet MAC User Guide www.xilinx.com 51UG074 (v2.2) February 22, 2010Client InterfaceRReceive (RX) Client – 8-bit Wide InterfaceIn this configuration, EMAC#CLIENTRXD[15:8] and EMAC#CLIENTRXDVLDMSWsignals are left unconnected.Normal Frame ReceptionThe timing of a normal inbound frame transfer is shown in Figure 3-15. The client mustaccept data at any time; there is no buffering within the Ethernet MAC to allow for receiveclient latency. After frame reception begins, data is transferred on consecutive clock cyclesto the receive client until the frame is complete. The Ethernet MAC asserts theEMAC#CLIENTRXGOODFRAME signal to indicate successful receipt of the frame andthe ability to analyze the frame by the client.Frame parameters (destination address, source address, LT, data, and optionally FCS) aresupplied on the data bus as shown in the timing diagram. The abbreviations are the sameas those described in Table 3-1, page 39.If the LT field has a length interpretation, the inbound frame could be padded to meet theEthernet minimum frame size specification. This padding is not passed to the client in thedata payload; an exception is when FCS passing is enabled. See “Client-Supplied FCSPassing,” page 54.Therefore, when client-supplied FCS passing is disabled, EMAC#CLIENTRXDVLD = 0between frames for the duration of the padding field (if present), the FCS field, carrierextension (if present), the IFG following the frame, and the preamble field of the nextframe. When client-supplied FCS passing is enabled, EMAC#CLIENTRXDVLD = 0between frames for the duration of carrier extension (if present), the IFG, and the preamblefield of the following frame.EMAC#CLIENTRXGOODFRAME, EMAC#CLIENTRXBADFRAME TimingAlthough the timing diagram in Figure 3-15 shows the EMAC#CLIENTRXGOODFRAMEsignal asserted shortly after the last valid data on EMAC#CLIENTRXD[7:0], this is notalways the case. The EMAC#CLIENTRXGOODFRAME orEMAC#CLIENTRXBADFRAME signals are asserted only after completing all the framechecks. This is after receipt of the FCS field (and after reception of the carrier extension ifpresent).Therefore, either EMAC#CLIENTRXGOODFRAME or EMAC#CLIENTRXBADFRAME isasserted following frame reception at the beginning of the IFG.Figure 3-15: Normal Frame ReceptionEMAC#CLIENTRXD[7:0]EMAC#CLIENTRXGOODFRAMEEMAC#CLIENTRXBADFRAMEDA SA DATAL/Tug074_3_17_051704CLIENTEMAC#RXCLIENTCLKINEMAC#CLIENTRXDVLDwww.BDTIC.com/XILINX |
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