The FPGA-based controller

www.davidwyatt.me.uk : Volumetric LED display : The FPGA-based controller

Introduction

As stated on the front page, the controller for the cube used a Xilinx Virtex-II XC2V6000 FPGA on a very versatile development board (produced specifically for 6.111). All the control logic for the cube was implemented in the FPGA - a PC was only used for developing and programming the board. In effect, we designed our own special-purpose 3D graphics processor (plus a few applications to run on it) inside the FPGA using the Verilog hardware description language.

Structure

The logic implemented in the FPGA was divided into two subsections (one of which was developed by each member of the project team). These subsections, and their components, were as follows:

• Application modules:
  • 3D Pong
  • 2D cellular automaton (Conway's "Game of Life") - patterns: blank, glider, spaceship, flower
  • 3D cellular automaton - patterns: blank, "explosion" (three cells in a line), eight corners, random
  • Music visualiser - oscilloscope mode, ripple mode
  • MIT trip-let (M from the side, I from the top, T from the front) - with or without PWM for varying the brightness in waves down the letters
• Display output module:
  • 3D display output
  • SVGA output (for debugging purposes)

They were connected by a "space buffer", a 512-bit area of RAM inside the FPGA containing the instantaneous state of each LED - output from the selected application and read by the display output module.

See the image gallery for pictures of the applications and the other aspects of the system.

Files

For more details on the controller, including the full Verilog source code, see the following:

• The final report we wrote on the project (3.9Mb PDF)
• Overall block diagram (PNG) (or PDF)
• Block diagrams of the application modules (PNG) (or PDF)
• Display output module block diagram (PNG) (or PDF, which also shows details of the orthographic projection used in the SVGA output)