Arty – Building MicroBlaze in Vivado

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The Arty board is the next generation of the very useful LX9 MicroBoard however, it takes account of advances in devices and interfacing. I ordered mine just before I recently flew to Japan, and it was waiting for me when I returned.

arty

 

The Arty is marketed as the perfect development platform for MicroBlaze applications as such when I opened my Arty the first thing I wanted to do was a new build from scratch of a MicroBlaze system. This way I could really understand the ease (or not) with which it could be developed, in the end it was very easy to create both the hardware application and create the simple software to say hello world.

To get MicroBlaze up and running on my Arty I did the following

  • Download and install the most update version of Vivado (remember to install the Vivado Design Edition)
  • Redeem the license for the Vivado SW which comes with the Arty
  • Download the Arty board definitions
  • Create the hardware definition within a new Vivado project
  • Build the hardware definition and export it to SDK
  • Create out SW application – This needs Hardware Definition, Board Support Package and Application SW.

While it may seem daunting these stages can be achieved quickly, also I am not going to talk you through how to do the first two points as they are very straight forward.

Which brings us to downloading the board definitions, these are available at the following link https://reference.digilentinc.com/vivado:boardfiles Once you have downloaded the board files you need to extract the Arty board definitions and store it within your Vivado installation <VIVADO DIRECTORY>/data/boards/ on my system the path is C:\Xilinx\Vivado\2015.3\data\boards\board_files

Within the arty directory you will then see the board definition XML and most helpfully a mig.prj this is the settings for the memory interface generator for if we wish to use the DDR on the arty (and we will of course).

This enables us to create a new project and select the Arty board, which is our next step

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Once we have the project created the next step is to create the MicroBlaze system, to do this we need to create a block diagram within which we can create our system. You can create a block diagram by selecting Create Block Diagram option under the Flow Navigator on the left of Vivado

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Once the block diagram is open we need to add the following things to it

  • MicroBlaze System – See end of blog for customisation
  • Memory Interface Generator – This uses the arty settings so it is just a case of scrolling through and generating the options
  • AXI UART lite – for communication externally – double click on it to set your RS232 options the default is 9600 no parity one stop bit
  • AXI Timer
  • AXI Interrupt Controller – We need a concatenate block to drive the interrupt from the timer and the AXI UART lite
  • AXI BRAM Controller and BRAM for the AXI Data and Instruction Cache
  • Clocking wizard to output a 166.667 MHz Clock and a 200 MHz Clock
  • MicroBlaze Debug Module
  • AXI Peripheral Interconnect to connect to the timer and UART
  • AXI Memory Interconnect to connect to the MIG (DDR) and the AXI BRAM controller
  • Processor Reset System

The clocking of the MicroBlaze and all AXI peripherals should use the output clock from the MIG (ui_clk) while the MCM reset from the MIG block should be fed back to the processor reset system DCM input, the ui_clk_rst goes to the ext_reset_in on the reset block.

The clock wizard outputs connects as below

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The rest of the connections are pretty straight forward AXI connections, the only difference is the need to add in a MicroBlaze Local DLMB and ILMB memory we can use the Run Block Automation Option (MicroBlaze) available on top of the block diagram editor.

When it is all complete your diagram will look like the below

Arty_vivado

The one thing we have not done by this point is to connect up the IO on the design to those on the board. We can do this by selecting on the board tab within the block diagram

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We can then right click on a signal we wish to use and select Connect Board Component as below

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It is then just a simple case of selecting the existing IP to connect it to

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Do this for the following

  • Sys_clk – 100 MHz clock on the Arty
  • DDR3_SDRAM – the DDR on the arty
  • USB_UART – How we will say hello world
  • Reset – Reset input

This saves us from having to write a XDC file with the pin locations needed to ensure we use the correct IO with the board.

With this completed we can validate our design and we should not get any warnings – if you have any address issues see he Address Editor tab mine looked like below when it was validated OK

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Once it has validated OK you are in a position that you can build the hardware, and export the hardware definition to SDK.

I will post another blog tomorrow on how to get the SDK side of things up and running but below is the result

arty_hello

Below are the MicroBlaze customisations

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