Receive (Rx) Client - 8-Bit Wide Interface - Xilinx Virtex-4 User Manual

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Receive (RX) Client – 8-bit Wide Interface
In this configuration, EMAC#CLIENTRXD[15:8] and EMAC#CLIENTRXDVLDMSW
signals are left unconnected.
Normal Frame Reception
The timing of a normal inbound frame transfer is shown in
accept data at any time; there is no buffering within the Ethernet MAC to allow for receive
client latency. After frame reception begins, data is transferred on consecutive clock cycles
to the receive client until the frame is complete. The Ethernet MAC asserts the
EMAC#CLIENTRXGOODFRAME signal to indicate successful receipt of the frame and
the ability to analyze the frame by the client.
CLIENTEMAC#RXCLIENTCLKIN
EMAC#CLIENTRXD[7:0]
EMAC#CLIENTRXDVLD
EMAC#CLIENTRXGOODFRAME
EMAC#CLIENTRXBADFRAME
Frame parameters (destination address, source address, LT, data, and optionally FCS) are
supplied on the data bus as shown in the timing diagram. The abbreviations are the same
as those described in
If the LT field has a length interpretation, the inbound frame could be padded to meet the
Ethernet minimum frame size specification. This padding is not passed to the client in the
data payload; an exception is when FCS passing is enabled. See
Passing," page
Therefore, when client-supplied FCS passing is disabled, EMAC#CLIENTRXDVLD = 0
between frames for the duration of the padding field (if present), the FCS field, carrier
extension (if present), the IFG following the frame, and the preamble field of the next
frame. When client-supplied FCS passing is enabled, EMAC#CLIENTRXDVLD = 0
between frames for the duration of carrier extension (if present), the IFG, and the preamble
field of the following frame.
EMAC#CLIENTRXGOODFRAME, EMAC#CLIENTRXBADFRAME Timing
Although the timing diagram in
signal asserted shortly after the last valid data on EMAC#CLIENTRXD[7:0], this is not
always the case. The EMAC#CLIENTRXGOODFRAME or
EMAC#CLIENTRXBADFRAME signals are asserted only after completing all the frame
checks. This is after receipt of the FCS field (and after reception of the carrier extension if
present).
Therefore, either EMAC#CLIENTRXGOODFRAME or EMAC#CLIENTRXBADFRAME is
asserted following frame reception at the beginning of the IFG.
www.BDTIC.com/XILINX
Embedded Tri-Mode Ethernet MAC User Guide
UG074 (v2.2) February 22, 2010
DA
Figure 3-15: Normal Frame Reception
Table 3-1, page 39.
54.
Figure 3-15
www.xilinx.com
Figure 3-15. The client must
SA L/T DATA
"Client-Supplied FCS
shows the EMAC#CLIENTRXGOODFRAME
Client Interface
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