Interfacing a VGA Monitor to Xilinx XC3S200 FPGA
Lecturer: Dr. Edward Gatt [e-mail]
Laboratory Tutors: Dr. Ivan Grech [e-mail]
Mr. Owen Casha [e-mail]
Assessment: 60 % Examination
40 % Assignment  Tutorial Sheet (20%) / Project (20%)
Objectives
" Design a simple 3-bit VGA Controller using a VHDL code
" Implement the controller such that a VGA monitor can be interfaced to a
Xilinx XC3S200 FPGA
N.B. Since the implementation will be made on the Spartan-3 Starter Kit Board, the
students are encouraged to read through the following user guide before
starting their assignment:
http://lark.tu-sofia.bg/asic/labs/s3demo/Digilent_S3.pdf
to familiarise with its environment. In addition this document includes
information on the VGA Display interfacing.
Architecture Proposal
clk_in
clk_in
clk_in
clk_in
clk_in
clk_in
VGA Controller
VGA Controller
VGA Controller
VGA Controller
arst_in
arst_in
arst_in
arst_in
arst_in
arst_in
colour_in[2:0]
colour_in[2:0]
colour_in[2:0]
colour_in[2:0]
colour_in[2:0]
colour_in[2:0]
N/O
N/O
25 MHz
25 MHz
25 MHz
Button Switch
Button Switch
red_out
red_out
red_out
red_out
red_out
red_out
green_out
green_out
green_out
green_out
green_out
green_out
blue_out
blue_out
blue_out
blue_out
blue_out
blue_out
hs_out
hs_out
hs_out
hs_out
hs_out
hs_out
vs_out
vs_out
vs_out
vs_out
vs_out
vs_out
Dip Switches
Dip Switches
MNE 2202  Hardware Description Languages 1/4
Input/Output Requirements:
clk_in Main synchronization clock signal
arst_in Asynchronous reset
colour_in [2:0] Input data word which determines the colour of the
circle
red_out Red Colour Enable
green_out Green Colour Enable
blue_out Blue Colour Enable
hs_out Horizontal sync signal
colour_in =  100
vs_out Vertical sync signal
Problem Description
colour_in 2 colour_in 1 colour_in 0 Circle Colour Background
Colour
0 0 0 BLACK WHITE
0 0 1 BLUE
0 1 0 GREEN
0 1 1 CYAN
1 0 0 RED BLACK
1 0 1 MAGENTA
1 1 0 YELLOW
1 1 1 WHITE
The function of the VGA controller is to display a coloured circle located at the centre
of the screen and that has a radius of 250 pixels. The colour of the circle and that of
the background should be controlled by the user via the three dip switches connected
to the colour_in 3-bit bus according to the above table. The monitor should be
operated on a 640 x 480 resolution mode with refresh rate of 60 Hz.
The equation of a circle is given by:
(y - y1)2 +(x - x1)2 = R2
(y - y1)×(y - y1)+(x - x1)×(x - x1)= R× R
where R is the radius of the circle and (x1,y1) are the coordinates of the centre of the
circle.
MNE 2202  Hardware Description Languages 2/4
VGA Port on the Spartan-3 Development Board
MNE 2202  Hardware Description Languages 3/4
25 MHz
MNE 2202  Hardware Description Languages 4/4