Cmod A7 - Getting Started with Microblaze


This guide is obsolete, the updated guide can be found here.



This guide will provide a step by step walk-through of creating a Microblaze based hardware design using the Vivado IP Integrator for the Cmod A7 FPGA board.

Microblaze is a soft IP core from Xilinx that will implement a microprocessor entirely within the Xilinx FPGA general purpose memory and logic fabric. For this tutorial, we are going to add a Microblaze IP block using the Vivado IP Integrator tool.

A UART ( universal asynchronous receiver/transmitter ) IP block will also be added to communicate between the host PC and the soft processor core running on the Cmod A7.

General Design Flow

I. Vivado

  • Open Vivado and select Cmod A7 board
  • Create an new Vivado Project
  • Create empty block design workspace inside the new project
  • Add required IP blocks using the IP integrator tool and build Hardware Design
  • Validate and save block design
  • Create HDL system wrapper
  • Run design Synthesis and Implementation
  • Generate Bit File
  • Export Hardware Design including the generated bit stream file to SDK tool
  • Launch SDK

Now the Hardware design is exported to the SDK tool. The Vivado to SDK hand-off is done internally through Vivado. We will use SDK to create a Software application that will use the customized board interface data and FPGA hardware configuration by importing the hardware design information from Vivado.


  • Create new application project and select default Hello World template
  • Program FPGA
  • Run configuration by selecting the correct UART COM Port and Baud Rate



  • Digilent Cmod A7 FPGA Board
  • Micro USB Cable
    • For both UART communication and JTAG programming


  • Xilinx Vivado 2015.X+
    • Should work for 2016.X as well
  • Xilinx SDK
    • Same version as your vivado installation
  • Serial Terminal Application
    • Tera Term is used in this tutorial

Board Support Files

  • Board Support Files – These files will describe GPIO interfaces on your board and make it easier to select your FPGA board and add GPIO IP blocks.


1. Creating the Project

When you first run Vivado this will be the main start window where you can create a new project or open a recent one.

1.1) Click on Create New Project. Choose the Project Name and Location such that there are no blank spaces. This is an important naming convention to follow for project names, file names and location paths.
Underscore in a good substitute for empty spaces.

It is good practice to have a dedicated folder for Vivado Projects, preferably with the smallest possible path length. Example: C:/Vivado_Projects.

Name your Project and select the Project location and click Next.

1.2) Choose Project Type as RTL Project. Leave the - do not specify sources box unchecked and click Next.

1.3) We will not be importing or creating any files here, so click Next until the part select screen.

1.4) If you have completed the Board Support File Wiki guide, select Boards.
Cmod A7 should be displayed in the selection list. A mismatch in selecting the correct board name will cause errors. Select the Cmod A7 and click Next.

1.5) A summary of the new project design sources and target device is displayed. Click Finish.

2. Creating New Block Design

This is the main project window where you can create a IP based block design or add RTL based design sources. The flow navigator panel on the left provides multiple options on how to create a hardware design, perform simulation, run synthesis and implementation and generate a bit file. You can also program the board directly from Vivado with the generated bit file for an RTL project using the Hardware Manager.

For our design, we will use the IP Integrator to create a new block design.

2.1) On the left you should see the Flow Navigator. Select Create Block Design under the IP Integrator. Give a name to your design (without any empty spaces) and click Ok.

You have created a new block design.

3. Adding the Microblaze Processor & Configuration

3.1) Click the Add IP button and search for Microblaze.

Double click Microblaze to add it to your block design.

3.2) Click the Board tab (Highlighted in orange below) and find System Clock.

This list contains all of the components defined in the board file you installed before. These are already configured to work with several Vivado IPs.
3.3) Click and drag System Clock out onto your block design to create a new clock wizard with our system clock connected to it.

3.2) Click Run Block Automation to open the Block automation for the Microblaze processor.

Here you can choose how much memory to give your Microblaze processor. Configure the options to match the picture below, then click OK.

3.3) Running the block automation will auto-generate a set of additional IP blocks which will be added to our hardware design automatically based on the options selected in the previous step. Do not click on Run Connection Automation yet.

4. Adding the Cell Ram Component

4.1) Click the Board tab (Highlighted in orange below)

4.2) Click and drag the Cell RAM component onto the empty block design. Vivado will automatically connect the Cellular RAM to the AXI EMC IP block. Then connect the rdclk pin to clk_out1 of the Clocking Wizard.

5. Adding Peripheral Components

5.1) Go into the Boards tab again and find the USB UART component. Click and drag this onto the block design to add the Uartlite block to your design.

5.2) Click Run Connection Automation in the green banner. Check the All Automation checkbox and click OK.

This will create one AXI Interconnect for the Block Memory and another for peripheral components.
Click the Regenerate Layout button to rearrange your block design.

6. Validating Design and making an HDL Wrapper

6.1) Select Validate Design. This will check for design and connection errors.
6.2) After the design validation step we will proceed with creating a HDL System Wrapper. Click on the Sources tab and find your block design.

Right click on your block design and click Create HDL Wrapper. Let Vivado manage wrapper and auto-update and click OK.

This will create a top module in VHDL and will allow you to generate a bitstream.

7. Generating Bit File

7.1) In the top toolbar in Vivado, click Generate Bitstream. This can also be found in the Flow Navigator panel on the left, under Program and Debug.
If you haven't already saved your design, you will get a prompt to save the block design.
7.2) The bit file generation will begin. The tool will run Synthesis and Implementation. After both synthesis and implementation have been successfully completed, the bit file will be created. You will find a status bar of Synthesis and Implementation running on the top right corner of the project window.

This process can take anywhere from 2 to 20 minutes depending on your computer.
7.3) After the bitstream has been generated, a message prompt will pop-up on the screen. You don't have to open the Implemented Design for this demo. Just click Cancel.

8. Exporting Hardware Design to SDK

8.1) On the main toolbar, click File and select Export Hardware. Check the box to Include Bitstream and click OK. This will export the hardware design with system wrapper for the Software Development Tool - Vivado SDK.

A new file directory will be created under Hello_World.SDK similar to the Vivado hardware design project name. Two other files, .sysdef and .hdf are also created. This step essentially creates a new SDK Workspace.
8.2) On the main toolbar, click File and then Launch SDK. Leave both of the dropdown menus as their default Local to Project and click OK. This will open Xilinx SDK and import your hardware.

9. Inside Xilinx SDK

9.1) The HW design specification and included IP blocks are displayed in the system.hdf file. Xilinx SDK is independent of Vivado, i.e. from this point, you can create your SW project in C/C++ on top of the exported HW design. If necessary, you can also launch SDK directly from the SDK folder created in the main Vivado Project directory.

From this point, if you need to go back to Vivado and make changes to the HW design, then it is recommended to close the SDK window and make the required HW design edits in Vivado. After this you must follow the sequence of creating a new HDL wrapper, save design and bit file generation. This new bit file and system wrapper must then be exported to SDK.

9.2) Within the Project Explorer tab on the left, you can see your hardware platform.

system is the name of your block design created in Vivado. This hardware platform has all the HW design definitions, IP interfaces that have been added, external output signal information and local memory address information.

10. Creating New Application Project in SDK

10.1) Click the New dropdown arrow and select Application Project.

Give your project a name that has no empty spaces and click Next.
10.2) Select Hello World from the list of templates and click OK.

You will see two new folders in the Project Explorer panel.

  • display_hello_world which contains all the binaries, .C and .H (Header) files
  • display_hello_world_bsp which is the board support folder

display_hello_world is our main working source folder. This also contains an important file shown here which is the “lscript.ld”. This is a Xilinx auto generated linker script file. Double click on this file to open.

10.3) Back in the Project Explorer, double click and open helloworld.c under the src folder.

This is the main .C file which will print hello world in the console when executed.

11. Programming FPGA with Bit File

11.1) Make sure that the Cmod A7 is turned on and connected to the host PC via both the JTAG USB port and the UART USB port.

On the top toolbar, click the Program FPGA button.
11.2) Click Program to program your FPGA with your hardware design.

12. Setting up UART Terminal

12.1) Open up a Serial Terminal application (Tera Term). Connect to the Cmod A7 UART port with a baud rate of 9600. This baud rate can be altered in your block design by double clicking the Uartlite block.

13. Program the Microblaze Processor

13.1) Back in SDK, select your Hello_world project and click the Run As… button. Select Launch on Hardware (System Debugger) and click OK.

13.2) Your program will run and you should see Hello World pop up inside of your Serial Terminal.