Open Source Risc-V on the Xilinx Artix-7 35T Arty – Part 1

Configuring and programming the 100 € Xilinx Arty development board with an open source implementation of the Risc-V ISA from SiFive.

RISC-V is an open instruction set architecture (ISA). It is based on reduced instruction set computing (RISC), with a “small” instruction set. In contrast to most ISAs like x86 and ARM, the RISC-V ISA can be freely used for any purpose, permitting anyone to design, manufacture and sell RISC-V chips and software. The project startet in 2010 at the University of California, Berkeley and has grown rapidly.

Important is, that RISC-V, it not a processor! It is an ISA specification, with different implementations. However there is a reference processor implementation (Rocket), chip generation tool and a GNU compiler toolchain provided by the RISC-V Foundation.

SiFive, is the commercial company, which was founded by some of the inventors of RISC-V. They have their first ASIC implementations, e.g. the HiFive1. The integrated SiFive E31 Coreplex is similar to the Freedom E300, which could be placed on the Xilinx Arty board.

Installing the Software

There are several ways to install the Xilinx Vivado IDE. One possibility is to download the full package – Xilinx_Vivado_SDK_2017.1_0415_1.tar.gz. After the download go to the download folder and extract vivado and change into the folder.

$ tar -xvf Xilinx_Vivado_SDK_2017.1_0415_1.tar.gz
$ cd Xilinx_Vivado_SDK_2017.1_0415_1/

Start the setup for installing Vivado.

$ $ ./xsetup

Installation of the Vivado Toolchain

Click through the installation and create an installation directory.

Install the Xilinx Cable drivers.

$ cd /data2/Risc-V/Vivado/Vivado/2017.1/data/xicom/cable_drivers/lin64/install_script/install_drivers
$ sudo ./install_drivers

Install the BSP for the Digilent Arty Board.

$ cd /tmp
$ git clone
$ sudo cp -r vivado-boards/new/board_files/* /data2/Risc-V/Vivado/Vivado/2017.1/data/boards/board_files/

Open the bashrc with an editor.

$ vim ~/.bashrc

Add the PATH export of the Vivado toolchain to the end of the bashrc

export PATH=$PATH:/data2/Risc-V/Vivado/Vivado/2017.1/bin

Add Olimex to udev

Set the udev rules to allow the device to be accessed by the plugdevgroup to allow access without sudo.

$ sudo vim /etc/udev/rules.d/99-openocd.rules

Add this to the file.

# For the Olimex Device
SUBSYSTEM=="usb", ATTR{idVendor}=="15ba",ATTR{idProduct}=="002a", MODE="664", GROUP="plugdev"
SUBSYSTEM=="tty", ATTRS{idVendor}=="15ba",ATTRS{idProduct}=="002a", MODE="664", GROUP="plugdev"

Add the user to the plugdev group and reload the udev rules.

$ sudo usermod -a -G plugdev >>username<<
$ sudo udevadm control --reload-rules

SiFive FPGA and Software

Checkout the Software for the FPGA.
Time depends highly on the internet connection.

$ cd /data2/Risc-V/
$ git clone --recursive

Setting up the SDK

$ cd /data2/Risc-V/
$ git clone --recursive
$ cd freedom-e-sdk
$ sudo apt-get install autoconf automake libmpc-dev libmpfr-dev libgmp-dev gawk bison flex texinfo libtool libusb-1.0-0-dev make g++ pkg-config libexpat1-dev zlib1g-dev
$ make tools

In the folder “freedom-e-sdk” the Makefile must be edited

$ vim Makefile

Change the BOARD and PROGRAM in the Makefile to the following.

# Default target
BOARD ?= freedom-e300-arty
PROGRAM ?= demo_gpio

Build the software for the Arty board.

$ make software

Install Risc-V GNU Toolchain to the system.

$ cd riscv-gnu-toolchain
$ ./configure
$ sudo make

After that it it possible to translate the software to integrate it in the mcs file.

$ cd ../software/demo_gpio/
$ risc64-unknown-elf-objcopy -O binary demo_gpio demo_gpio.bin

Change to the “freedom” folder.
And add the demo_gpio to the mcs build.

$ cd /data2/Risc-V/freedom/
$ vim fpga/e300artydevkit/Makefile

Build the MCS, which includes the bitstream.
$ make -f Makefile.e300artydevkit mcs

Now it is time to program the ARTY board.
This could be done with the vivado software.

$ vivado

Klick on “Open Hardware Manger”.

“Open target” -> “Open New Target…”

Finish and see results

Press the “prog” button and see the results.

Further Readings

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