GTS AXI Multichannel DMA IP for PCI Express User Guide

ID 847470
Date 5/06/2025
Public

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4.4.1. PCIe AXI-Stream TX Interface (ss_tx_st)

The outbound packet towards the link is transmitted through this PCIe AXI-Stream TX interface with separate header and data interfaces. These interfaces support single segments with data widths of 16 bytes (128 bits) and 32 bytes (256 bits). These interfaces should be connected to the corresponding AXI-Stream TX interface of the GTS AXI Streaming IP.

For information on this interface, refer to AXI4-Stream Transmit (TX) Interface.

Interface clock: axi_st_clk

DWIDTH depends on the PCIe mode selected:

  • 256 bits for Gen4 1x4
  • 128 bits for Gen3 1x4
Table 34.  PCIe AXI-Stream TX Interface
Signal Name Direction Description
app_ss_st_tx_tvalid Output Indicates that the source is driving a valid transfer.
ss_app_st_tx_tready Input Indicates that the sink can accept a transfer in the current cycle.
app_ss_st_tx_tdata[DWIDTH-1:0] Output Data bus used to provide the data that is passing across the interface.
app_ss_st_tx_tkeep[DWIDTH/8-1:0] Output

A byte qualifier used to indicate whether the content of the associated byte is valid.

The invalid bytes are allowed only during the app_ss_st_tx_tlast cycle.

Note: Sparse tkeep is not supported.

app_ss_st_tx_tlast Output Indicates End of Data/Command Transmission.
app_ss_st_tx_tuser_hvalid Output Indicates the tuser_hdr is valid in the current cycle.
app_ss_st_tx_tuser_hdr[DWIDTH-1:0] Output

Carries header format for the current cycle of data transfer.

For the bit positions and mapping, refer to Header Format.