6–10
Chapter 6: IP Core Interfaces
Avalon-ST RX Interface
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
shows the mapping of Avalon-ST RX packet to PCI Express TLPs for TLPs
for a four dword header with non-qword addresses with a 64-bit bus. Note that the
address of the first dword is 0x4. The address of the first enabled byte is 0xC. This
example shows one valid word in the first dword, as indicated by the
rx_st_be
signal.
illustrates the timing of the RX interface when the Application Layer
backpressures the Arria V GZ Hard IP for PCI Express by deasserting
rx_st_ready
.
The
rx_st_valid
signal deasserts within three cycles after
rx_st_ready
is deasserted.
In this example,
rx_st_valid
is deasserted in the next cycle.
rx_st_data
is held until
the Application Layer is able to accept it.
Figure 6–6. 64-Bit Avalon-ST rx_st_data
<n>
Cycle Definitions for 4-Dword Header TLPs with Non-Qword Addresses
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]
.
pld_clk
rx_st_data[63:32]
rx_st_data[31:0]
rx_st_sop
rx_st_eop
rx_st_bardec[7:0]
rx_st_be[7:4]
rx_st_be[3:0]
header1
header3
data0
data2
header0
header2
data1
10
C
F
F
Figure 6–7. 64-Bit Application Layer Backpressures Transaction Layer
pld_clk
rx_st_data[63:0]
rx_st_sop
rx_st_eop
rx_st_ready
rx_st_valid
000
. 010
.
CCCC0002CCCC0001
CC
. CC
. CC
. CC
. CC
. CC
.