Getting Started with Zynq

Overview

This guide will provide a step by step walk-through of creating a hardware design using the Vivado IP Integrator for the Zybo board.

At the end of this tutorial you will have:

  • Created a simple hardware design incorporating the on board LEDs and switches.
  • Created a .C project in XIlinx Vivado SDK tieing the on board LEDs and switches together using the hardware design shown in the previous step.

Prerequisites

Hardware

  • Digilent's Zybo Development Board and a Micro USB cable for UART communication and JTAG programming

Software

  • Xilinx Vivado 2015.X with the SDK package.

Board Support Files

  • Zybo Support Files
    • These files will describe GPIO interfaces on your board and make it easier to select your board in the initial design setup and add GPIO IP blocks in the block design
    • Follow this Wiki guide Vivado Board Files for Digilent 7-Series FPGA Boards on how to install Board Support Files for Vivado 2015.X

Tutorial

General Design Flow

I. Vivado

  • Open Vivado and select Zybo 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.

II. SDK

  • Create new application project and select default Hello World template
  • Program FPGA and run application

1. Creating a New 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.

1.2) You will be presented with the project creation wizard. Click Next.

1.3) Enter a project name and location the click Next.

1.4) Select RTL Project and click Next.

1.5) This demo does not use any existing sources, existing IP or constraints. Click through the next three screens.

1.6) Select Boards and select the Zybo board file. Click Next and then Finish.


2. Creating a New Block Design

2.1) Once the process has completed, click Create Block Design in the flow navigator.

2.2) Click OK.

2.3) A blank Block Design will open up.


3. Add the Zynq IP & GPIO Blocks

3.1) Click the Add IP button and search for ZYNQ. Double click on ZYNQ7 Processing System to place the bare Zynq block.

3.2) Click the Run Block Automation link



Your Zynq block should now look like the picture below.
3.3) Click the Add IP icon again, this time search for “gpio” and add the AXI GPIO core.

3.4) Double-click on new axi_gpio_0 core that was just added to bring up the customizing window. Under the IP Configuration tab check the Enable Dual Channel box. Click OK.

3.5) Add another GPIO core by repeating step 3.4 but do not enable dual channel.


4. Run the Connection Automation Tool

4.1) The connection automation tool will add the required logic blocks for the demo. Select Run Connection Automation highlighted in blue.

4.2) Check the box by All Automation. Select GPIO under axi_gpio_0 and select btns_4bits in the Board Part Interface drop-down box.

4.3) Select GPIO2 under axi_gpio_0 and select swts_4bits in the drop-down box.

4.4) Select GPIO under axi_gpio_1 and select leds_4bits in the drop-down box and hit OK.

4.5) This process will add:
  * The AXI interconnect
  * Processor System Reset 
  * The board parts for the buttons, switches and LEDs.

4.6) Next let's clean up our Block Design. Click the Regenerate Layout button to rearrange your block design.


5. Generate HDL Wrapper and Validate Design

5.1) Select Validate Design. This will check for design and connection errors.
5.2) After the design validation step we will proceed with creating a HDL System Wrapper. In the block design window, under the Design Sources tab, right-click on the block diagram file. We labeled it “design_1.bd” and select Create HDL Wrapper.

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


6. Generate the Bitstream

6.1) Click on Generate Bitstream at the bottom of the Flow Navigator. Wait for the process to complete and click OK.


7. Export hardware files for SDK

7.1) Go to file→Export→Export Hardware… Make sure to check the box for Include bitstream then click OK.


8. Launch SDK

8.1) Go to File→Launch SDK and click OK.


9. Create a new Hello World Application Project in SDK

9.1) Go to File→New→Application Project.

9.2) Enter the project details:
  * Project name: "getting_started_with_ZYBO"
  * Hardware Platform: design_1_weapper_he_platform_0
  * Processor: ps7_cortexas9_0
  * Languate: C
  * OS Platform: standalone
  * Board Support Package: Create New (leave default name)

9.3) The Hello World demo is a good starting point for this demo. Click Next, select Hello World and click Finish. This process will add two directories to the project explorer.
9.4) Expand getting_started_with_ZYBO then open src and double click on “helloworld.c”. This is the default Hello World C code.


10. Creating Our Own Hello World

10.1) Copy and paste the code below into the helloworld.c file.
/*****************************************************
Getting Started Guide for Zybo
 
This demo displays the status of the switches on the
LEDs and prints a message to the serial communication
when a button is pressed.
 
Terminal Settings:
   -Baud: 115200
   -Data bits: 8
   -Parity: no
   -Stop bits: 1
 
1/6/14: Created by MarshallW
****************************************************/
 
#include <stdio.h>
#include "platform.h"
#include <xgpio.h>
#include "xparameters.h"
#include "sleep.h"
 
int main()
{
   XGpio input, output;
   int button_data = 0;
   int switch_data = 0;
 
   XGpio_Initialize(&input, XPAR_AXI_GPIO_0_DEVICE_ID);	//initialize input XGpio variable
   XGpio_Initialize(&output, XPAR_AXI_GPIO_1_DEVICE_ID);	//initialize output XGpio variable
 
   XGpio_SetDataDirection(&input, 1, 0xF);			//set first channel tristate buffer to input
   XGpio_SetDataDirection(&input, 2, 0xF);			//set second channel tristate buffer to input
 
   XGpio_SetDataDirection(&output, 1, 0x0);		//set first channel tristate buffer to output
 
   init_platform();
 
   while(1){
      switch_data = XGpio_DiscreteRead(&input, 2);	//get switch data
 
      XGpio_DiscreteWrite(&output, 1, switch_data);	//write switch data to the LEDs
 
      button_data = XGpio_DiscreteRead(&input, 1);	//get button data
 
      //print message dependent on whether one or more buttons are pressed
      if(button_data == 0b0000){} //do nothing
 
      else if(button_data == 0b0001)
         xil_printf("button 0 pressed\n\r");
 
      else if(button_data == 0b0010)
         xil_printf("button 1 pressed\n\r");
 
      else if(button_data == 0b0100)
         xil_printf("button 2 pressed\n\r");
 
      else if(button_data == 0b1000)
         xil_printf("button 3 pressed\n\r");
 
      else
         xil_printf("multiple buttons pressed\n\r");
 
      usleep(200000);			//delay
 
   }
   cleanup_platform();
   return 0;
}

11. Run the Project

11.1) Make sure that the Zybo is connected to the host PC via the UART USB Port and that JP5 is set to JTAG. To program the FPGA, on the top toolbar, click the Program FPGA button.
11.2) Save the project. The project will automatically build.
11.3) Right click the getting_started_with_ZYBO directory and select run as → Launch on Hardware(System Debugger).
11.4) The demo will be running on the ZYBO. Try playing around with the 4 switches (labeled SW0-SW3). Doing so should light its respective LED. Also over the serial port, pressing each button (labeled BTN0-BTN3) will produce the message “button x pressed”.
11.5) Tera Term or any serial terminal will work as a Console for displaying the output of the BTN's.
Set up the terminal as: