Xilinx Spartan-3E starter kit : VGA

Hello everyone,

I'm new to velocityreviews. I'm searching for an answer about a problem I have with VGA port on Xilinx Spartan-3E starter kit.

For the moment and for tests, i'm trying to use switches as color selector for the entire screen (each switch is mapped on a color bit, red, green and blue color bits).

The resolution is 640x480 @ 60Hz. I use the timings shown in starter kit user guide. The monitor detect the correct resolution and the correct frequency. But I've a problem with the colors. The screen show the correct color for a few seconds and then become black. Each time I change the state of a switch, the screen do this. I tried with constants for each color bit. For example : '1' for red, '0' for green and '1' for blue, but the screen remains totally black.

I've correctly edit the ucf constraint file like in the user guide.

Has anyone an idea about the problem?

Thanks for your help.

Peak.

Peak