GTS AXI Multichannel DMA IP for PCI Express* User Guide

ID 847470
Date 8/25/2025
Public
Document Table of Contents

A.1.1.5. AXI-MM Write (H2D) and Read (D2H) Manager

The AXI-MM interface is used to transfer data between the host and device through the memory-mapped interface. You can enable the Memory-Mapped interface by selecting the AXI-MM User Interface type in the IP Parameter Editor. The GTS AXI MCDMA IP supports a single AXI4 interface, where the H2D path is connected to the write channels while the D2H path is connected to the read channels of the interface.

AXI-MM Write (H2D)

The AXI-MM Write interface is used to write H2D DMA data to the AXI-MM subordinate in the user logic through the memory-mapped interface. The Write interface can issue AXI-MM write commands with a maximum of 512B burst size. The data width of this interface varies based on the PCIe Mode IP parameter configuration: 128-bit (Gen3 1x4), 256-bit (Gen4 1x4), or 512-bit (Gen4 1x8). The readyAllowance of this port is enabled, allowing the interface to transfer data up to N additional write command cycles after the ready signal has been deasserted. The corresponding AXI-MM subordinate interface in the user logic supports this attribute to avoid data loss. The value of <N> for the H2D AXI-MM Interface is as follows:

  • 512-bit data width is 16.
  • 256-bit data width is 32.
  • 128-bit data width is 64.

AXI-MM Read (D2H)

The AXI-MM Read interface is used to read D2H DMA data from the AXI-MM subordinate in the user logic through the memory-mapped interface. The Read interface can issue AXI-MM read commands with a maximum of 512B burst size. The data width of this interface varies based on the PCIe Mode IP parameter configuration: 128-bit (Gen3 1x4), 256-bit (Gen4 1x4), or 512-bit (Gen4 1x8). The readyAllowance of this port is enabled, allowing the interface to transfer up to N additional write command cycles after the ready signal has been deasserted. The corresponding AXI-MM subordinate interface in the user logic supports this attribute to avoid data loss. The value of <N> for the D2H AXI-MM Interface is as follows:

  • 512-bit data width is 16.
  • 256-bit data width is 32.
  • 128-bit data width is 64.