VERILOG example using VIVADO 2015 with ZYBO FPGA board

Aim

In this tutorial I will use Verilog with¬† classical FPGA design. I bought perfect modern FPGA board ZYBO (ZYnq BOard) based on Xilinx Z-7010 from Digilent but latest tools from Xilinx VIVADO 2015.2 more focused on AP SoC programming while I want to just pure FPGA design without any linuxes bootloaders etc. So I wrote this tutorial to help people like me ūüôā

In this example we make simple scheme: 2 signals IN and 4 OUT.

Preconditions: Adding Zybo Board to Vivado

Vivado 2015.2 under Windows 7 64 bit was used with 16 GB of RAM.

Before using Zybo with Vivado you should add Zybo Definitions File to Vivado.

1. Good source for Board Definition files is Zynqbook website.Download The_Zynq_Book_Tutorial_Sources_Aug15.zip

2. Copy zybo folder with content from Archive path \sources\zybo\setup\board_part into D:\Xilinx\Vivado\2015.2\data\boards\board_files (if D:\Xilinx\Vivado\2015.2 is my PC you probably have C:\Xilinx etc…)

3. In board_files you should see other boards. Now our Zybo known by Vivado.

4. Download  ZYBO_Master.xdc from Digilent website unpack constraints files on local hard disk for example on Desktop.

Phase 1. Preparation.

I have latest Vivado Design Edition from Xilinx which comes with Digilent Zybo board.

Launch your Vivado.

Create new project

New Project

Click Next

Set project name.

Set project name to gates2,

Keep rest settings unchanged unless you know what you doing.

Project Type

Keep default RTL(Register Transfer Level) project, Press Next

Add sources

In this tutorial we decided to use Verilog language so make sure it set correctly. Simulator language you can keep unchanged.

Click on “+” – Select – Create File.

Create Source File

Set Filename to gates2. Keep the rest unchaged. Press OK. Press Next.

Add Existing IP

Click Next.

Add Constraints

Click “+”, Add Files.

Add Constraint file we downloaded at Precondition step.

Make sure: Copy constraints files into project – Checked.

Click – Next

Default Part

Click on boards and select Zybo. If you still don’t have it follow steps in Preconditions: Adding Zybo board to Vivado.

If you don’t see ZYBO goto Preconditions Step.

Next.

New Project Summary

Finish

Phase 2. Editing Project

Project files generated and ready for your design.

We will implement 2 input gates and 4 output basic gates and, or,  xor and  nor.

Define I/O ports as below

OK

Select Verilog Design

Click on Source file in Project Manager>Sources>Design Sources – Source code on Right-hand side should appear.

 

Changes to source code.

Modify Verilog file – add lines as highlighted below.

wire a,b;
reg [3:0]z;
always @(a or b)
begin
z[0] = a & b;
z[1] = a | b;
z[2] = a ^ b;
z[3] = !(a | b);
end

 

Create top file

Rightclick on Design Sources and select Add Sources.

1. Add or create design souces.

2. “+” > Create File

File Type :Verilog,

File name: top_gates2

OK

Finish

Define Module

Add sw and led as on image below.

Replace default source code.

`timescale 1ns / 1ps
module top_gates2(
    input [1:0] sw,
    output [3:0] led
    );
    
    gates2 C1(
        .a(sw[0]),
        .b(sw[1]),
        .z(led)
    );
endmodule

Top Design

We have single top design interface file which use our gates2 design as component.

top design

Make sure our top file became parent of gates2 file. Otherwise set it manually with Set as Top.

Amend Constraints file

Select xdc file from Sources>Constraints

Changes in xdc file

Uncomment lines of I/O ports we need to use.

Save file.

Phase 3  РSynthesis and uploading to device.

At Synthesis phase we convert our circuit from register transfer level (RTL) into  a design implementation in terms of logic gates.

In Flow Navigator on Lefthand side.:

Next steps can be Simulation>Run Simulation or RTL Analysis>Schematic but we skip them in this tutorial and come directly to Synthesis>Run Synthesis.

Synthesis complention

Leave default Run Implementation

OK

Generate Bitstream

Select Generate Bitstream

OK

 

Final

Pay attention to jumpers.

JP7 – It should set to USB.

JP5 can be JTAG or QSPI

Connect ZYBO to PC with Micro-USB cable.

Photo taken from http://marsee101.blog19.fc2.com/blog-entry-2745.html

Program ZYBO

 

 

Next

Next

Make sure you have similar setting like on picture below.

Select xc7z010_1

Next

Finish

Program device > xc7z010_1

Program

As confirmation of successfull upload Greed Led will set

Use switches to confirm and, or, xor and nor operations.

Archive of project available.

PDF version of this lesson available.

Reference

1. http://www.slideshare.net/MaryalaSrinivas/verilog-tutorial

2. http://www.instructables.com/id/Learn-Verilog-A-Brief-Tutorial-Series-on-FPGA-Desi/?ALLSTEPS

3. The ZYNQ BOOK – Make sure you download not only book archive but also tutorials book with sources.

4. HDL Chip Design- A Practical Guide for Designing, Synthesizing and Simulating ASICs and FPGAs Using VHDL or Verilog. By Douglas J. Smith

5. ZYBO Reference Manual

Feedback

boris@borisivanov.com

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  1. Pingback: Using Digilent’s PMOD8LD with ZYBO FPGA board | Digital Mordor

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