Chapter 6: IP Core Interfaces
6–9
Avalon-ST RX Interface
June 2012
Altera Corporation
Stratix V Hard IP for PCI Express
1
The Avalon-ST protocol, as defined in
Avalon Interface Specifications
, is big endian,
while the Hard IP for PCI Express packs symbols into words in little endian format.
Consequently, you cannot use the standard data format adapters available in Qsys.
illustrates the mapping of Avalon-ST RX packets to PCI Express TLPs for a
three dword header with qword aligned addresses. Note that the byte enables
indicate the first byte of data is not valid and the last dword of data has a single valid
byte.
shows the mapping of Avalon-ST RX packets to PCI Express TLPs for TLPs
for a four dword header with qword aligned addresses with a 64-bit bus.
Figure 6–3. 64-Bit Avalon-ST rx_st_data
<n>
Cycle Definition for 3-Dword Header TLPs with Non-Qword Aligned Address
pld_clk
rx_st_data[63:32]
rx_st_data[31:0]
rx_st_sop
rx_st_eop
rx_st_be[7:4]
rx_st_be[3:0]
Header1
Data0
Data2
Header0
Header2
Data1
F
F
F
Figure 6–4. 64-Bit Avalon-ST rx_st_data<n> Cycle Definition for 3-Dword Header TLPs with Qword Aligned Address
Note to
(1)
rx_st_be[7:4]
corresponds to
rx_st_data[63:32]
.
rx_st_be[3:0]
corresponds to
rx_st_data[31:0]
clk
rx_st_data[63:32]
rx_st_data[31:0]
rx_st_sop
rx_st_eop
rx_st_be[7:4]
rx_st_be[3:0]
Header 1
Data1
Data3
Header 0
Header2
Data0
Data2
F
1
F
E
Figure 6–5. 64-Bit Avalon-ST rx_st_data
<n>
Cycle Definitions for 4-Dword Header TLPs with Qword Aligned Addresses
pld_clk
rx_st_data[63:32]
rx_st_data[31:0]
rx_st_sop
rx_st_eop
rx_st_be[7:4]
rx_st_be[3:0]
header1
header3
data1
header0
header2
data0
F
F