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6–12
Chapter 6: IP Core Interfaces
Avalon-ST RX Interface
Stratix V Hard IP for PCI Express
June 2012
Altera Corporation
shows the mapping of 128-bit Avalon-ST RX packets to PCI Express TLPs
for TLPs with a 3 dword header and non-qword aligned addresses. In this case,
bits[127:96] represent Data0 because address[2] in the TLP header is set. The assertion
of
rx_st_empty
in a
rx_st_eop
cycle indicates valid data on the lower 64 bits of
rx_st_data
.
shows the mapping of 128-bit Avalon-ST RX packets to PCI Express TLPs
for a four dword header with non-qword aligned addresses. In this example,
rx_st_empty
is low because the data is valid for all 128 bits in the
rx_st_eop
cycle.
Figure 6–10. 128-Bit Avalon-ST rx_st_data
<n>
Cycle Definition for 3-Dword Header TLPs with non-Qword Aligned
Addresses
rx_st_valid
rx_st_data[127:96]
rx_st_data[95:64]
rx_st_data[63:32]
rx_st_data[31:0]
rx_st_sop
rx_st_eop
rx_st_empty
Data0
Data 4
Header 2
Data 3
Header 1
Data 2
Data (n)
Header 0
Data 1
Data (n-1)
pld_clk
Figure 6–11. 128-Bit Avalon-ST rx_st_data Cycle Definition for 4-Dword Header TLPs with non-Qword Aligned Addresses
pld_clk
rx_st_valid
rx_st_data[127:96]
rx_st_data[95:64]
rx_st_data[63:32]
rx_st_data[31:0]
rx_st_sop
rx_st_eop
rx_st_empty
Header 3
Data 2
Header 2
Data 1
Data n
Header 1
Data 0
Data n-1
Header 0
Data n-2