6–14
Chapter 6: IP Core Interfaces
Avalon-ST RX Interface
Stratix V Hard IP for PCI Express
June 2012
Altera Corporation
illustrates back-to-back transmission on the 128-bit Avalon-ST RX
interface with no idle cycles between the assertion of
rx_st_eop
and
rx_st_sop
.
illustrates a two-cycle packet with valid data in the lower qword
(
rx_st_data[63:0]
) and a one-cycle packet where the
rx_st_sop
and
rx_st_eop
occur
in the same cycle.
f
For a complete description of the TLP packet header formats, refer to
Transaction Layer Packet (TLP) Header Formats
.
Single Packet Per Cycle
In single packer per cycle mode, all received TLPs start at the lower 128-bit boundary
on a 256-bit Avalon-ST interface. Turn on
Enable Multiple Packets per Cycle
on the
System Settings tab of the parameter editor to change multiple packets per cycle.
Figure 6–14. 128-Bit Avalon-ST Interface Back-to-Back Transmission
pld_clk
rx_st_data[127:0]
rx_st_sop
rx_st_eop
rx_st_empty
rx_st_ready
rx_st_valid
rx_st_err
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
BB ...
...
BB
Figure 6–15. 128-Bit Packet Examples of rx_st_empty and Single-Cycle Packet
pld_clk
rx_st_data[127:0]
rx_st_sop
rx_st_eop
rx_st_empty
rx_st_ready
rx_st_valid
0000090
1C0020000F0000000100004
450AC89000012FE0D10004