color_maker user manual

Title color_maker-s3ansk (simple VGA tester)
Author Nikolaos Kavvadias (C) 2014
Source Mike Field (for the VGA controller; see AUTHORS)
Release Date 09 June 2014
Version 1.0.0
Rev. history  


Initial release for the Spartan-3AN Starter kit board.

1. Introduction

color_maker is a simple design for testing VGA output. This version of the color_maker produces 4-bit RGB color (R2G1B1), corresponding to 16 distinct colors out of a total of 4096 (R3G4B4) that are supported by the Xilinx Spartan-3AN starter kit board. The 4 available slide switches (SW3-SW0) are used for setting a specific color. The following table summarizes the exercised colors.

R G B Description
00 0 0 Black (Noir)
00 0 1 Blue
00 1 0 Green
00 1 1 Cyan
01 0 0 Brown
01 0 1 Deep Purple
01 1 0 Light Green
01 1 1 Medium Cyan
10 0 0 Blood Red
10 0 1 Medium Purple
10 1 0 Chartreuse
10 1 1 Light Cyan
11 0 0 Red
11 0 1 Magenta
11 1 0 Yellow
11 1 1 White

For the standard VGA resolution (640x480@60Hz), a 25MHz clock is used, as produced by the clockdiv clock divider (divide by 2). The VGA controller is implemented by vgactrl.vhd. The color selection logic is very simple and directly assigns SW3-SW2 to the R (two levels), SW1 to G and SW0 to the B component. For 800x600@72Hz, a 50 MHz clock should be used.

The vga_controller design has been adapted from the work by Mike Field:

2. File listing

The color_maker distribution includes the following files:

/color_maker-s3ansk Top-level directory
AUTHORS List of authors.
COPYING 3-clause modified BSD license.
README This file.
README.html HTML version of README.
README.pdf PDF version of README.
clockdiv.vhd Configurable, portable, clock divider.
color_maker.vhd Color assignment logic.
color_maker_top.ucf User Constraints File for the XC3S700AN-FGG484-4 device.
color_maker_top.vhd The top-level RTL VHDL design file. Bash shell script for synthesizing the color_maker design with Xilinx ISE.
impact_s3ansk.bat Windows Batch file for automatically invoking Xilinx IMPACT in order to download the generated bitstream to the target hardware. Bash script for generating the HTML and PDF versions.
vgactrl.vhd RTL VHDL code for the VGA controller. Standard Makefile for command-line usage of ISE.

3. Usage

The color_maker distribution includes scripts for logic synthesis automation supporting Xilinx ISE. The corresponding synthesis script can be edited in order to specify the following for adapting to the user's setup:

3.1. Running the synthesis script

For running the Xilinx ISE synthesis tool, generating FPGA configuration bistream and downloading to the target device, execute the corresponding script from within the color_maker-s3ansk directory:

$ ./

In order to successfully run the entire process, you should have the target board connected to the host and it should be powered on.

The synthesis procedure invokes several Xilinx ISE command-line tools for logic synthesis as described in the corresponding Makefile, found in the the color_maker-s3ansk directory.

Typically, this process includes the following:

  • Generation of the *.xst synthesis script file.
  • Generation of the *.ngc gate-level netlist file in NGC format.
  • Building the corresponding *.ngd file.
  • Performing mapping using map which generates the corresponding *.ncd file.
  • Place-and-routing using par which updates the corresponding *.ncd file.
  • Tracing critical paths using trce for reoptimizing the *.ncd file.
  • Bitstream generation (*.bit) using bitgen, however with unused pins.

As a result of this process, the color_maker_top.bit bitstream file is produced.

Then, the shell script invokes the Xilinx IMPACT tool by a Windows batch file, automatically passing a series of commands that are necessary for configuring the target FPGA device:

  1. Set mode to binary scan.
setMode -bs
  1. Set cable port detection to auto (tests various ports).
setCable -p auto
  1. Identify parts and their order in the scan chain.
  1. Assign the bitstream to the first part in the scan chain.
assignFile -p 1 -file color_maker_top.bit
  1. Program the selected device.
program -p 1 -onlyFpga
  1. Exit IMPACT.

4. Prerequisities