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Chapter 6: IP Core Interfaces
6–25
Avalon-ST TX Interface
June 2012
Altera Corporation
Stratix V Hard IP for PCI Express
illustrates back-to-back transmission of 128-bit packets with idle dead
cycles between the assertion of
tx_st_eop
and
tx_st_sop
.
illustrates the timing of the TX interface when the Stratix V Hard IP for
PCI Express backpressures the Application Layer by deasserting
tx_st_ready
.
Because the
readyLatency
is two cycles, the Application Layer deasserts
tx_st_valid
after two cycles and holds
tx_st_data
until two cycles after
tx_st_ready
is reasserted
Data Alignment and Timing for the 256-Bit Avalon-ST TX Interface
Refer to
Figure 6–16 on page 6–15
layout of headers and data for the 256-bit
Avalon-ST packets with qword aligned and qword unaligned addresses.
Figure 6–28. 128-Bit Back-to-Back Transmission on the Avalon-ST TX Interface
pld_clk
tx_st_data[127:0]
tx_st_sop
tx_st_eop
tx_st_empty
tx_st_ready
tx_st_valid
tx_st_err
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Figure 6–29. 128-Bit Hard IP Backpressures the Application Layer for TX Transactions
pld_clk
tx_st_data[127:0]
tx_st_sop
tx_st_eop
tx_st_empty
tx_st_ready
tx_st_valid
tx_st_err
000
CC...
CC...
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