PYNQ Tutorial 1: GPIO

Objective

After you complete this tutorial, you should be able to:

• Install a Linux OS on a MicroSD card for the ZYNQ FPGA.
• Create a Hello World project for ZYNQ FPGA.

Required Hardware

• A ZYNQ FPGA board that supports PYNQ
• A USB micro cable
• An Ethernet cable (also a USB-to-Ethernet adapter if your laptop doesn't have Ethernet)
• A MicroSD card (16 GB)
• A MicroSD card reader (if your laptop doesn't have one)

Required Software

Download and install the following software tools:

• Vivado 2019.1 (tested) with board files installed
  • Retired Zybo, Zybo-Z7-10, Zybo-Z7-20: https://github.com/Digilent/vivado-boards/tree/master
  • PYNQ Z1, PYNQ Z2: https://pynq.readthedocs.io/en/v2.6.1/overlay_design_methodology/board_settings.html
• Win32DiskImager (https://win32diskimager.org/)
• PuTTY (https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html)
• WinSCP (https://winscp.net/eng/index.php?)

Download the PYNQ Linux OS image file depending on your FPGA board. Use the image v3.0.1.

• Retired Zybo, Zybo-Z7-10, Zybo-Z7-20: https://github.com/nick-petrovsky/PYNQ-ZYBO
• PYNQ Z1, PYNQ Z2, and others: https://www.pynq.io/boards.html

1. FPGA Setup

1.1. MicroSD Setup

In this step, you are going to install Linux OS on the MicroSD card. Follow these steps:

• Connect the MicroSD to the laptop via SD reader.
• Extract the Linux image file to your laptop to obtain the .img file.
• Open the Win32DiskImager program.
• Select your image file (the .img file).
• Make sure the selected device is the MicroSD card.
• Click Write to write to the MicroSD card. Wait until finished.
• Safety remove the MicroSD card and insert the MicroSD card into your FPGA board.

1.2. Boot the FPGA

In this step, your MicroSD should be ready and inserted into your FPGA. Follow these steps to boot the FPGA. In this example, I use the ZYBO board, but for other boards, it should be similar.

• Insert MicroSD to your board.
• Make sure the boot jumper is set to SD.
• Make sure the power supply jumper is correct, either USB or external adaptor.
• Connect the USB cable and Ethernet cable to your laptop.
• Connect the board's power supply (or some boards can use power from the USB) and turn on the switch power.
• Open the PuTTY program, setup the Serial line according to the COM port on your laptop (every laptop may be different, open Device Manager to see your COM port) and Speed 115200. Then click Open.

• Wait until the boot process is complete.

• Some boards are automatically logged in. But if your board is required to login, usually this is the credentials:
  • User ID: xilinx
  • Password: xilinx
• Setup your computer's IP address to the following:
  • IP address: 192.168.2.100
  • Subnet mask: 255.255.255.0

• Open a web browser and enter the URL: http://192.168.2.99:9090. The Jupyter Notebook will be loaded. The password is xilinx.

• [IMPORTANT] How to turn off the board? To prevent MicroSD card corruption, when turning off the board, perform a shutdown process with the command:

sudo shutdown -h now

• Wait until the FPGA board is completely shut down before turning off the board's power supply.

2. Hello World Project

2.1. Create Vivado Project

In this section, we are going to create a new Vivado project that consists of simple AXI GPIO IP.

• Open the Vivado program and create a new project from menu File, Project, New.

• [IMPORTANT] Select the folder where you want to create the project. Do not use a read-only location (usually the My Document in C: drive is read-only), and the folder location must not have spaces.

• Select Project Type as RTL Project.

• Select your FPGA board. Then, click Next, and Finish.

2.2. Create Block Design

At this point, you should be able to create a new project. The next step is to create a block design.

• On the left side (the Flow Navigator), select the Create Block Design menu.

• Give the block design name design_1.

• Click the Add IP button, then add the ZYNQ7 Processing System IP.

• Click the Run Block Automation button to configure the ZYNQ7 Processing System IP based on the board library.

• Click OK on the Run Block Automation window.

• Click Add IP, then add the AXI GPIO IP.

• Click the Run Connection Automation menu to automatically connect the AXI GPIO IP to the Zynq IP.

• Checklist only S_AXI, then click OK to make the AXI GPIO connection.

• In the block design, double-click the AXI GPIO IP to configure it. Check the All Outputs option to configure the GPIO to be an output port. Then click OK.

• In the Sources section, right-click on the design_1 design block, then select the Create HDL Wrapper menu.

• Click OK to generate.

2.3. Compile the System

In this section, we are going to compile the design.

• On the left side (the Flow Navigator), select the Generate Block Design menu. In the Synthesis Options section, select the Global option. In the Run Settings section, Number of jobs is the setting for how many CPU cores are used to perform this process. The more, the faster the process will finish.

• On the left side (the Flow Navigator), select the Run Synthesis menu. Configure the Number of jobs, and then click OK. Wait until the synthesis is complete.

• A window will appear after the synthesis process is complete. Next, click OK to run the Run Implementation process. Configure the Number of jobs, and then click OK. Wait until the implementation is complete.

• A window will appear after the implementation process is complete. Next, select the Generate Bitstream option and click OK. Configure the Number of jobs, and then click OK. Wait until the generate bitstream is complete.

• A window will appear after the generate bitstream process is complete. Close this window.

2.4. Export the Compiled Files

At this point, your design is already compiled. The next step is to program the FPGA and test the design.

• Export the block design file from the File, Export, Export Block Design menu.

• Export to the default location and name it design_1.tcl.

• Export the bitstream file from the File, Export, Export Bitstream File menu.

• Export to the same location as the block design and name it design_1.bit. This name must be the same as the name of the block design.

• Using Windows Explorer, go into the following project folder. Then you will find the design_1.hwh file.

<YOUR_PROJECT_LOCATION>\part_1\part_1.srcs\sources_1\bd\design_1\hw_hand

• Move the design_1.hwh file to the main project folder. So, there will be three files:
  • design_1.tcl
  • design_1.bit
  • design_1.hwh

• Power on the board as in the previous FPGA boot procedure. Open WinSCP program, then connect it to the FPGA board. Open WinSCP and enter Hostname: 192.168.2.99, User name: xilinx, Password: xilinx.

• On the left side, navigate to the Vivado project folder location. You will see the three required files. Then, drag and drop the three files from left to right to upload.

2.5. Test the Design

At this point, the required files to program the FPGA are already on the board. The next step is to create Jupyter Notebook files.

• Open a web browser and open Jupyter Notebook on the board. Create a new file from menu New, Python 3 (pykernel).
• Write the following Python code to test the design: https://github.com/yohanes-erwin/pemrograman_zynq/tree/main/pynq_part_1
• In this program, we write the value 168 to GPIO, and then the value is read back. You can try with other values.