VGA controller and FMS3818 video chip

[BlackOps]

vga controller chip

Hello,

i am using XUPV2P board with FMS3818 video chip on it.

i have my VGA controller which outputs 8 bit R,G and B signals, and hsync and vsync signals..

to show this data on CRT monitor, i must first input this data in the video chip.. then, directly to the VGA connector. (hsync and vsync signals will be routed directly to the VGA connector bypassing video chip, as shown on manual schematic)

i will also route my final clock signal to the video chip.

and my question is:what i must put on BLANK pin of the video chip?

according to its datasheet, when BLANK is Low, pixed data are ignored.. so i assume that i must always toggle BLANK - HIGH, right?

next question is:
what i must put on SYNC pin of the video chip?

datasheet says that SYNC =H, activates sync current from Ios for sync-on-green video signals, and SYNC = L, turns off a current source, Ios that is connected to the green D/A converter.

so.. when i have to turn it on or off? or do i always have to toggle it HIGH?

thanks

 

[honnaraj.t]

fms3818

HI,
EVEN I AM FACING SAME PROBLEM ... DID YOU GET ANY ANSWER FOR YOU DOUBT.........
PLEASE SEND ME ANY MATERIAL IF YOU HAVE ..............

 

[BlackOps]

vga chip

yes, toggle !SYNC = 0, and !BLANK = 1 always if you want to display your pixels on screen.

SYNC is composite green signal... you dont need it thats why u should toggle it LOW

When !BLANK is HIGH, it means that your pixels are Valid, and they are displayed on screen. so you must toggle it ON.

also connect your controller Clock shifted 180deg to the VGA_PIXEL_CLOCK input of the chip. good luck. i did wrote simple VGA controller based on examples for XUPV2P board.

 

[honnaraj.t]

8-bit video chip

thanks for reply..............
k i understood !sync and blank,,,,,,,,,,
now my question is i have only 65535 memory so i need to generate i mage on that memory and display on the screen.............. but i not getting how to calculate vsync and hsync signals for my screen size,.......... is there any standard way of calculating the clock cycle..................please tell me how to generate hsync and vsync for different resolution screen............................................

 

[param]

vga vsync signal

Hi,
VGA standard is 640 X 480.
Hence there should be 480 hsyncs within in one vsync
and 640 pixels in one hsync.
The period for 640 pixels is represented as high on Blank signal.

The Formula which relates thepixel clock, frame rate,Hsyn and Vsync are

Horizontal Sync Frequency = Frame Rate * Number of Pixels per line * Multiplication Factor.

Multiplication factor is amount of Hsync Trace Period spend for each line.

The MF(Multiplication Factor) can be calculated as

MF = HDP/(HDP + HNDP)


HDP = Horizontal Display period.
HNDP= Horizontal Non Display period.

(HDP + HNDP gives the Total display period for each line. )

The formula for Frame rate is

Frame rate = Fclk / ( (VDP + VNDP) * (HDP + HNDP ) )

VDP = Vertical Display period
VNDP = Vertical Non Display Period
Fclk = Pixel Clock