Digital Signal Processing Reference
In-Depth Information
Table 10.1 The VGA Video Display Pin Assignments
Pin Name
DE1
DE2
UP3
UP2,
UP1
Pin
Type
Function of Pin
CLOCK
L1
50Mhz
N2
50Mhz
153
48Mhz
91
25Mhz
Input
2550MHz Clock
VGA_RED
B7
E10
228
236
Output
VGA Red Video Signal
(highest bit on DE1/2)
VGA_GREEN
A8
D12
122
237
Output
VGA Green Video
Signal (highest bit on
DE1/2)
VGA_BLUE
B10
B12
170
238
Output
VGA Blue Video Signal
(highest bit on DE1/2)
VGA_VSYNC
B11
D8
226
239
Output
VGA Connector Vertical
Sync Signal
VGA_HSYNC
A11
A7
227
240
Output
VGA Connector
Horizontal Sync Signal
10.7
Video Examples
For a simple video example with the VGA_SYNC function, the following
schematic produces a video simulation of a red LED. When the PB1 pushbutton
is hit, the color of the entire video screen will change from black to red. The
VGA_LED project setup is seen below:
VGA_SY NC
INPUT
OUTPUT
Clock_48Mhz
VGA_Red
clock_48Mhz
red
green
blue
red_out
green_out
blue_out
horiz_sy nc_out
v ert _sy nc_out
v ideo_on
pixel_clock
pixel_row[9..0]
pixel_column[9..0]
VCC
INPUT
OUTPUT
VGA_Green
PBSWITCH4
VCC
OUTPUT
VGA_Blue
OUTPUT
VGA_HSync
OUTPUT
VGA_VSync
GND
11
1
VGA_SYNC outputs the pixel row and column address. Pixel_row and
Pixel_column are normally inputs to user logic that in turn generates the RGB
color data. Here is a simple example that uses the pixel_column output to
generate the RGB inputs. Bits 7, 6, and 5 of the pixel_column count are
connected to the RGB data. Since bits 4 through 0 of pixel column are not
connected, RGB color data will only change once every 32 pixels across the
screen. This in turn generates a sequence of color bars in the video output. The
color bars display the eight different colors that can be generated by the three
digital RGB outputs in the VGA_BAR project.
