Problem with LVDS display link.

[buenos]

hi

I designed a digital board with a TFT display and a VGA output. The TFT output is 4 LVDS pairs.


There is no picture on the screen, sometimes stripes, but most of the time, its just white. when the display on the VGA changes resolution, or something like that, there are stripes on the TFT then white again.

There are reference designs for the processor (AMD Geode-LX) and for the LVDS seralizer (National DS90C385A), i just connected averything in the same way: 6-8bit compatibility mode. The processor has a parallel RGB output, it goes to the LVDS serializer. The LCD is also in 6/8-bit mode .

There are the signals on the parallel RGB bus, and as well as on the LVDS bus. I measured ny scope.

If we check the signals on the scope, it seems teh signals are not crossing each other. is it normal?

 

[Iouri]

lvds display

can you do it again please and use AC coupling instead of DC?

 

[OlVi]

displaylink lcd controller

And use active probes, as LVDS lines are loaded too much with passive probes

 

[Iouri]

parallel rgb to lvds

Actually, go to info mode in your monitor and make sure it is support resolution what you selected

 

[buenos]

lvds display link

info mode? its an lcd panel.
for the testing: my colleagues will continue it, in another country. so i dont have the board anymore.

 

[jogur]

Re: LVDS display link.

Hi,

Please check the polarity and timings for HSYNC, VSYNC & Clock. & also the power up and power down voltage sequencing for LCD.

If every thing is fine configure the OSD register of LCD controller in color bar mode. This will display the color bars on the LCD.(A quick check to verify the funcionality).

Thanks