Adding Traffic Generators to Your Design - 2025.2 English - UG1701

AXI Traffic Generator kernels provide a method to inject traffic onto the I/O of your system design, AI Engine graph, or PL kernels during simulation. AMD provides a library that enables interfacing AXI4-Stream to mimic a streaming data flow for software and hardware emulation, and AXI4 memory mapped interface to mimic memory mapped data transfers for hardware emulation.

The AXI Traffic generators are provided as XO files which can be linked into your System project using the Vitis compiler (v++).  These XO files are called sim_ipc_axis_master_XY.xo and sim_ipc_axis_slave_ZW.xo where XY and ZW correspond to the number of bits in the PLIO interface. For example, sim_ipc_axis_master_128.xo provides an AXI4-Stream master data bus that is 128 bits wide. A wider interface allows the PL to achieve the same throughput at a lower clock frequency and allows the AI Engine array to maximize its memory bandwidth. However, the PLIO interface tiles are each 64 bits wide and they are a limited resource. Using one 64-bit PLIO interface at twice the clock speed provides an equivalent bandwidth to a 128-bit PLIO while using only one PLIO tile. This requires the PL to run at twice the clock speed and the optimal choice will vary from application to application.

Two steps are required to use the traffic generators in your system design:

1. Specify the connections between the traffic generator (sim_ipc) modules and their corresponding AXI4-Stream ports on the AI Engine array. This is typically done in the system.cfg file using the --connectivity.nk and --connectivity.sc commands, as described in Linking the System. The following is an example:

   [connectivity]
   nk=sim_ipc_axis_master:1:inst_sim_ipc_axis_master
   nk=sim_ipc_axis_slave:1:inst_sim_ipc_axis_slave
   stream_connect=sim_ipc_axis_master.M00_AXIS:ai_engine_0.DataIn
   stream_connect=ai_engine_0.DataOut:sim_ipc_axis_slave.S00_AXIS

   The syntax for connecting the sim_ipc_axis XO files is as follows.

   nk=sim_ipc_axis_master:<Number Of Masters>:<inst_name_1>.<inst_name_2>.<...>
   nk=sim_ipc_axis_slave:<Number Of Slaves>:<inst_name_1>.<inst_name_2>.<...>

   Where:

   • The sim_ipc_axis_master/slave specifies the XO kernel in your design
   • The <Number Of Masters> or <Number Of Slaves> field lets you specify up to 8 different traffic generator kernels in your design
   • The <inst_name> should be meaningful in your application

2. Next, add the XO files to the Vitis link command as shown below.

   Important: The traffic generator XO can only be used in hardware emulation with hw_emu target.

   v++ -l --platform <platform.xpfm> sim_ipc_axis_master_128.xo sim_ipc_axis_slave_128.xo libadf.a -target hw_emu --config system.cfg

For additional information on how to use XO files with the Vitis compiler, see Building the Device Binary in the Data Center Acceleration using Vitis (UG1700).