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IP Core Generation Workflow without an Embedded ARM Processor: Xilinx Kintex-7 KC705

This example shows how to use the HDL Coder™ IP Core Generation Workflow to develop reference designs for Xilinx® parts without an embedded ARM® processor present, but which still utilize the HDL Coder™ generated AXI interface to control the DUT. This example uses MATLAB as AXI Master IP from HDL Verifier™ to access the HDL Coder™ generated DUT registers by enabling the reference design parameter option Insert JTAG MATAB as AXI Master. You can then access DUT registers from MATLAB directly. Alternatively, you can use Xilinx JTAG AXI Master to access the DUT registers using Vivado Tcl Console by writing Tcl commands. For Xilinx JTAG AXI Master, you need to create a custom reference design. The FPGA design is implemented on the Xilinx Kintex-7 KC705 board.

Requirements

  • Xilinx Vivado Design Suite, with supported version listed in the HDL Coder documentation

  • Xilinx Kintex-7 KC705 development board

  • HDL Coder™ support package for Xilinx FPGA Boards

  • (Optional) HDL Verifier™ support package for Xilinx FPGA Boards

Xilinx Kintex-7 KC705 development board

Example Reference Designs

There are many designs which will benefit from using the HDL Coder™ IP Core Generation Workflow without using either an embedded ARM® processor or an Embedded Coder™ Support Package, but which still leverages the HDL Coder generated AXI4-Lite registers. These designs include:

  1. HDL Verifier™ MATLAB as AXI Master + HDL Coder™ IP Core

  2. Xilinx JTAG Master + HDL Coder™ IP Core

  3. MicroBlaze™ + HDL Coder™ IP Core

  4. PCIe Endpoint + HDL Coder™ IP Core

There are two reference designs included in this example:

  • The Default system reference design uses MathWorks IP and a MATLAB command line interface for issuing read and write commands by enabling the reference design parameter option "Insert JTAG MATAB as AXI Master". Note that to use this parameter, you must have HDL Verifier™ installed.

  • The Xilinx JTAG to AXI Master reference design uses Vivado IP for the JTAG to AXI Master and therefore requires using the Vivado Tcl console to issue reads and writes.

The two reference designs are nearly identical, except for the JTAG Master IP used in the block diagram shown below:

The reference design, "Xilinx JTAG to AXI Master", uses Vivado™ IP for the JTAG to AXI Master and therefore requires using the Vivado™ Tcl console to issue reads and writes:

1. HDL Verifier™ MATLAB as AXI Master reference design

Specify Insert JTAG MATLAB as AXI Master (HDL Verifier Required) to on in the Set Target Reference Design task of IP Core Generation workflow. This adds MATLAB AXI Master IP automatically into the reference design and connects to the DUT IP using AXI4 slave interface. The detailed steps to auto insert the MATLAB JTAG AXI Master in the reference design are discussed in the following section.

Execute the IP Core Workflow

The following instructions in this section applies to Default System reference design which uses MATLAB JTAG as AXI Master. Using this reference design, you can generate an HDL IP Core that blinks LEDs on the KC705 board.

1. Set up the Xilinx Vivado™ tool path by using the following command:

hdlsetuptoolpath('ToolName', 'Xilinx Vivado', 'ToolPath', 'C:\Xilinx\Vivado\2019.1\bin\vivado.bat');

Use your own Xilinx Vivado™ installation path when executing the command.

2. Open the Simulink model that implements LED blinking using the command:

open_system('hdlcoder_led_blinking')

3. Launch HDL Workflow Advisor from the hdlcoder_led_blinking/led_counter subsystem by right-clicking the led_counter subsystem, and selecting HDL Code > HDL Workflow Advisor.

4. In the Set Target > Set Target Device and Synthesis Tool task, for Target workflow, select IP Core Generation, For Target platform , select Xilinx Kintex-7 KC705 development board and Click Run This Task to run the Set Target Device and Synthesis Tool task

5. In the Set Target > Set Target Reference Design task, Choose Default System as reference design and set Insert JTAG MATLAB as AXI Master dropdown choice to on which is present in the reference design parameter options.

6. In the Set Target > Set Target Interface task, choose AXI4-Lite for Blink_frequency, Blink_direction, and Read_back. Choose LEDs General Purpose [0:7] for LED.

7. Run the remaining steps in the workflow to generate a bitstream and program the target device.

Notice that unlike the Zynq-based reference design, there is no Generate Software Interface Model task. This is shown in the following figure.

Determining Addresses from the IP Core Report

The base address for an HDL Coder™ IP Core is defined as 0x40000000 for the Default System reference design which uses MATLAB AXI Master IP. You can see this in the generated IP Core report as shown in the following figure.

The offsets can be found in the IP Core Report Register Address Mapping table:

HDL Verifier Command Line Interface

If HDL Verifier support package for Xilinx FPGA boards is installed and the reference design "MATLAB as AXI Master" reference design is selected, then a simple MATLAB command line interface can be use to access the IP core generated by HDL Coder.

1. create the AXI master object

h = aximaster('Xilinx')

2. Issue a simple write command. For example, to disable the DUT

h.writememory('40000004', 0)

3. To re-enable the DUT, use the following write command

h.writememory('40000004', 1)

4. Issue a read command. For example, to read the current counter value

h.readmemory('40000108',1)

5. Delete the object when done to free up the JTAG resource. If the object is not deleted, other JTAG operations such as programming the FPGA will fail.

delete(h)

2. Xilinx JTAG Master reference design

You need to create a custom reference design to use Xilinx JTAG AXI Master in reference design and then add the reference design files to the MATLAB path using addpath command.

To access the HDL Coder™ IP Core registers using Xilinx JTAG AXI Master, the base address is defined in reference design plugin file.

Vivado Tcl Commands for AXI Read and Write

This example will use the stand alone Vivado Tcl console for the basic commands to issue reads and writes. The following commands can be used to open the JTAG device and setup an 'enable' and 'disable' write to the DUT. These can be entered directly into the Vivado Tcl console or saved in a Tcl file and sourced. For simplicity, copy the following Tcl commands into a file "open_jtag.tcl":

  # Open connection to the JTAG Master
  open_hw
  connect_hw_server
  open_hw_target
  refresh_hw_device [lindex [get_hw_devices] 0]
  # Create some reads/writes
  create_hw_axi_txn wr_enable [get_hw_axis hw_axi_1] -address 44a0_0004 -data 0000_0001 -type write
  create_hw_axi_txn wr_disable [get_hw_axis hw_axi_1] -address 44a0_0004 -data 0000_0000 -type write

Now launch the Vivado™ Tcl console, sourcing the file you just created:

>> system('vivado -mode tcl -source open_jtag.tcl&')

When you are done using the JTAG Master, close the connection using the following Tcl commands:

  # Close and disconnect from the JTAG Master
  close_hw_target;
  disconnect_hw_server;

Summary

Using a JTAG to AXI Master is a simple way to interface with HDL Coder™ IP core registers in systems which do not have an embedded ARM® processor, such as the Kintex-7. This can be used as first step to debug stand alone HDL Coder™ IP cores, used prior to hand coding software for soft processors, such as MicroBlaze™, or as an easy way to tune parameters on a running system.