Configuring the Design for an AXI4-Lite Interface - 2024.1 English

Vitis Model Composer User Guide (UG1483)

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2024.1 English

In the example_dds design, Gateway In and Gateway Out blocks mark the boundary of the Cycle and Bit accurate FPGA portion of the Simulink design. Control of the DDS Compiler frequency is accomplished by “injecting” the correct value on the signals attached to the output port of Gateway In’s called phase_valid and phase_data. This is accomplished by modifying the Interface Options, as shown below for the phase_valid block.

Figure 1. Interface Options

As you can see, the Interface is specified as a slave AXI4-Lite Interface in Model Composer, which means that it will be transformed to a top-level AXI4-Lite interface.

The following options are also of particular interest:

Auto assign address offset
(Enabled) Each Gateway is associated with a register within the AXI4-Lite Interface and this control specifies that Automatic assignment of address offsets will take place in the design based on number of different Gateway Ins mapped to the AXI4‑Lite interface. Addresses are byte aligned to a 32-bit data width.
Address offset
(Disabled) This option is only enabled if Auto assign address offset is unchecked. It allows the user to manually override of Address Offset.
Interface Name
Assigns a unique name to this interface. This name can be used to differentiate between multiple AXI4-Lite interfaces in the design.
Important: The Interface Name must be composed of alphanumeric characters (lowercase alphabetic) or an underscore (_) only, and must begin with a lowercase alphabetic character. 'axi4_lite1' is acceptable, '1Axi4-Lite' is not.
The text you enter here is captured in the "Interface Documentation" that is automatically created when the design is exported to the Vivado IP catalog.

Configure the other Gateways in the design in a similar fashion.

Tip: As an alternative to using individual Gateway In/Out blocks for each AXI signal, you can use the Gateway In/Out AXI4-Stream blocks in the HDL/Interfaces library.