Errored Legacy Frame Transmission; Tx Av Traffic I/F - Xilinx LogiCORE IP Ethernet AVB Endpoint v2.4 User Manual

Errored Legacy Frame Transmission

X-Ref Target - Figure 6-2
The legacy_tx_underrun is provided to give full backwards compatibility between the
Legacy Traffic I/F and the client interface of the Tri-Mode Ethernet MAC. The
legacy_tx_underrun provides a mechanism to inject an error into a frame before
transmission is completed. This can occur, for example, if a FIFO connected to the Legacy
client empties during transmission.
To error the frame, the legacy_tx_underrun signal may be asserted during the data
transmission or up to 1 valid clock cycle after legacy_tx_data_valid goes low.

Tx AV Traffic I/F

The signals forming the Tx AV Traffic I/F are defined in
synchronous to the Tri-Mode Ethernet MAC transmitter clock, tx_clk, which must
always be qualified by the corresponding clock enable, tx_clk_en (see
("Talker Assumptions," page
input to the Ethernet AVB Endpoint on this interface.
This interface is intentionally very similar to the
that the legacy traffic does not contain a signal that is equivalent to av_tx_done.
Additionally, the AV does not contain a signal that is equivalent to
legacy_tx_underrun: no mechanism is currently provided on the AV interface to signal
an error in a frame which is currently undergoing transmission.
Ethernet AVB Endpoint User Guide
UG492 September 21, 2010
tx_clk
tx_clk_enable
legacy_tx_data[7:0]
legacy_tx_data_valid
legacy_tx_ack
legacy_tx_underrun
Figure 6-2: Legacy Frame Transmission with Underrun
www.xilinx.com
DA SA
31) for information about the expectations for the AV traffic
"Tx Legacy Traffic I/F."
Tx AV Traffic I/F
L/T DATA
Table 5-4. All signals are
Table 5-1). See
Note, however,
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