Building a RISC-V computer on an Arty A7-35T FPGA board with SaxonSoc

x11-usb-saxonsoc-arty

We built a RISC-V computer running the X Window System (X11) and using the SaxonSoc on an Arty A7-35T FPGA board from Digilent.
We used a USB keyboard and a USB mouse, as shown in the xterm at the top left of the featured image.
This computer is based on github.com/SpinalHDL/SaxonSoc and github.com/SpinalHDL/buildroot-spinal-saxon.

SaxonSoc

saxonsoc-console

The SaxonSoc is an SoC being developed by Charles Papon, the developer of the VexRiscv, and contributors.
Of course, the Soft CPU used in the SaxonSoc is the VexRiscv, a 32-bit RISC-V.
In the dev-0.3 branch currently under development, the supported FPGA boards are Radiona ULX3S, Digilent’s Arty A7 and Nexys A7.

RISC-V computer

We built a RISC-V computer with the following configuration.

  • RISC-V single board computer
    • Digilent Arty A7-35T
    • Alternative to Pmod usb_host_x4
      • USB connector to DIP adapter x 2
      • Breadboard, jumper wires
    • Digilent Pmod VGA
    • Digilent Pmod MicroSD
  • USB keyboard & mouse
  • VGA display
  • MicroSD
  • USB cable (power supply & USB-UART)

The main specifications of the RISC-V computer based on the Arty A7-35T are as follows.

  • CPU: Dual-core 32-bit RISC-V
    • ISA: RV32IMAFDC & AES custom extension
    • Operating frequency: 100 MHz
  • DRAM: 256 MB
  • Ethernet: 100 Mbps
  • USB: 2 ports
  • Display resolution: 1024 x 768
  • Storage
    • Onboard Flash: for OpenSBI & U-Boot
    • MicroSD: for Linux & rootfs

Summary

We built a RISC-V computer running the X Window System (X11) on an Arty A7-35T with the SaxonSoc.
The feature of this computer is that we can use a USB keyboard and a USB mouse.
Also, We think it’s good to be able to use the Window Maker as a window manager.