Global Memory Two Banks

This example of 2ddr is to demonstrate how to use multiple ddr and create buffers in each DDR.

KEY CONCEPTS: Multiple Banks

KEYWORDS: m_axi_auto_max_ports, sp, connectivity

This example demonstrates how buffers can be created in two different DDR(Global memory) banks.

By default, all the memory interfaces from all the kernels are connected to a single global memory bank. As a result, only one memory interface at a time can transfer data to and from the memory bank, limiting the performance of the kernel. If the FPGA contains only one DDR (or global) memory bank, this is the only option. However, some FPGA devices contain multiple DDR memory banks which allows us to customize the connections among the kernel memory interfaces and the DDR memory bank of a device by altering the default connection.

This example uses watermark application to demonstrate the utilization of multiple DDRs for full bandwidth. Input image is placed into Bank0 and kernel will read the input Image and write the output image to Bank1. Banks need to be specified using sp tags in apply_watermark.cfg file along with the port name and kernel name.

[connectivity]
sp=apply_watermark_1.input:DDR[0]
sp=apply_watermark_1.output:DDR[1]

EXCLUDED PLATFORMS:

  • All Embedded Zynq Platforms, i.e zc702, zcu102 etc

  • All Versal Platforms, i.e vck190 etc

  • Alveo U30

  • Alveo U50

  • Alveo U55

  • Samsung SmartSSD Computation Storage Drive

  • Samsung U.2 SmartSSD

  • X3 Compute Shell

  • All NoDMA Platforms, i.e u50 nodma etc

  • Versal V70

DESIGN FILES

Application code is located in the src directory. Accelerator binary files will be compiled to the xclbin directory. The xclbin directory is required by the Makefile and its contents will be filled during compilation. A listing of all the files in this example is shown below

data/golden.bmp
src/apply_watermark.cpp
src/host.cpp

Access these files in the github repo by clicking here.

COMMAND LINE ARGUMENTS

Once the environment has been configured, the application can be executed by

./gmem_2banks -x <apply_watermark XCLBIN> -i REPO_DIR/common/data/xilinx_img.bmp -c ./data/golden.bmp