Xilinx IP Ethernet AVB Endpoint v2.4 UG492 - Manual (Page 57)

Ethernet AVB Endpoint User Guide www.xilinx.com 57
UG492 September 21, 2010
Chapter 6
Ethernet AVB Endpoint Transmission
As illustrated in Figure 5-1 , data for transmission over an AVB network can be obtained
from three types of sources:
1. AV Traffic. For transmission from the “Tx AV Traffic I/F” of the core.
2. Precise Timing Protocol (PTP) Packets . Initiated by the software drivers using the
dedicated hardware “Tx PTP Packet Buffer.”
3. Legacy Traffic . For transmission from the “Tx Legacy Traffic I/F” of the core.
Tx Legacy Traffic I/F
The signals forming the Tx Legacy Traffic I/F are defined in Table 5-2 . All signals are
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
Table 5-1 ).
This interface is intentionally identical to the client transmitter interface of the supported
Xilinx Tri-Mode Ethernet MAC core (there is a one-to-one correspondence between signal
names of the block-level wrapper from the Tri-Mode Ethernet MAC example design, after
the legacy_ prefix is removed). This provides backwards compatibility–all existing MAC
client-side designs can connect to the legacy Ethernet port unmodified.