Design Details - 2023.2 English

Vitis Tutorials: AI Engine

Document ID
XD100
Release Date
2023-11-29
Version
2023.2 English

The design in this tutorial starts with a base platform containing the control interface and processing system (CIPS), NoC, AI Engine, and the interfaces among them. The Vitis compiler linker step builds on top of the base platform by adding the AI Engine graphs and PL kernels. To add the various functions in a system-level design, PL kernels are added to the base platform depending on the application (that is, the PL kernels present in each design might vary). An ADF graph is connected to an extensible Vitis platform where the graph I/Os are connected either to the platform ports or to ports on Vitis kernels through the Vitis compiler connectivity directives. In the design, the components are added by the Vitis compiler -l step (see make XSA) and include the following:

  • libadf.a

  • Data mover kernel (dma_hls.[hw|hw_emu].xo)

  • Connection interfaces defined in the system configuration file

To see a schematic view of the design with the extended platform as shown in the following figure, open the following in Vivado:

`build/gemm_$(MAT_DIMS)/x$(GEMM_INSTS)/[hw|hw_emu]/_x/link/vivado/vpl/prj/prj.xpr`

Image of GeMM AIE Vivado BD GeMM 32x32x32

In this design, the GeMM computation happens in multiple stages. The input is split and broadcast to multiple cores, the number of rows in Mat A and the number of columns in Mat B is split into several blocks, based on the cascade length and so on, and then each block in Mat A is multiplied with the corresponding block in Mat B, which generates blocks of outputs, which finally propagated for to the final output.

The datamover kernel provides the parallel inputs required by the GeMM AIE graph, and finally, the data coming out of the AI Engines is streamed to a PL kernel where it is checked against the expected constant pattern. If there is a mismatch, it is recorded in the variable errCnt, which is read in the host app to determine whether the test has passed or failed.

The system debugging and profiling IP (DPA) is added to the PL region of the device to capture AI Engine runtime trace data if the EN_TRACE option is enabled in the design. The dma_hls kernel and the AI Engine array interface are both operating at 312.5 MHz.

AI Engine and PL Kernels