STPC 1024x786 VGA

[knisbet]

Posted on June 18, 2003 at 20:10

STPC 1024x786 VGA

[knisbet]

Posted on May 29, 2003 at 17:16

I have an STPC on a Microsys development board.

I am working with a DOS application that requires 1024x786 VGA. I would like to use VESA mode 105h but I have not been able to make it work. I have tried VMODE.EXE without success. Any suggestions?

[thierry239955_st]

Posted on June 03, 2003 at 08:09

The VESA mode 105h is working fine on my own STPC Atlas evaluation board uses VMODE.EXE.

If VMODE.EXE can't initialize the mode on your board, it probably means the operation have been refused by the VGA BIOS. I don't know the configuration of the Microsys development board. You should check this: - if you use a Consumer-II board, the board is not configured in TV output mode (resolution limited to 640x480) - if you use an Atlas board, your VGA BIOS is not a TFT BIOS. You will be limited by the resolution of your TFT. - your frame buffer size is big enough for the mode, better to set 4MB of frame buffer. Farfalla

[knisbet]

Posted on June 03, 2003 at 11:33

Sorry, I should have added more detail to my question. I am using a development board from Microsys with an STPC Industrial chip. I have the frame buffer set to 4 Meg but when I try any mode above 103 the screen goes blank.

Thanks for the response

[thierry239955_st]

Posted on June 03, 2003 at 14:52

Hmm... it's look like your VGA screen is not able to synchronize the 1024x768 mode. Did you check with a recent screen, a 17'' or more? Some old or low price 14''/15'' are not able to display such resolution.

Did you notice if it is a stable screen with black pixels or if the synchronization have been lost? Recent screen have usually a special behaviour when not synchronized (a blinking led or some displayed message). You could also check the frequency of the horizontal and vertical synchronization signal directly on the VGA connector to verify the STPC is well initialized. For a 1024x768-60Hz, it should be arround 48.5KHz for the horizontal signal (and 60Hz for vertical - of course). Farfalla

[knisbet]

Posted on June 09, 2003 at 13:57

The monitor that I am using normally runs at 1024x768 on a PC. It looks as though the monitor is going into low power mode.

I measured the horiz. and Vert sync frequencies and they seem a little off the mark. Horiz. 51.4Khz Vert 62.9Khz Tha application will use a 7 inch monitor with a fixed horizontal frequency of 48.5Khz Thanks, Kim

[marios]

Posted on June 11, 2003 at 18:59

So you do get sync signals when you send the command. You should not be far. I'll try on my board (which has an Industrial) if it does the same thing. You said you were using vmode?

I suggest that you put a heat sink on your CPU. The temperature rises when you go into high-res modes. Which Microsys board is it? Felix

[knisbet]

Posted on June 11, 2003 at 19:07

I've been able to get to the correct H. Sync frequency by setting the Horizontal total register to A2h after calling vmode. Vmode sets it to 99h.

I'm using the SB0486 board form microsys. Thanks for the tip on the heatsink. Kim

[marios]

Posted on June 18, 2003 at 20:10

Yep, on my board (Magnipix MP901SH) I'm getting the same frequencies as you do. My monitor had no problem to catch it, so you're right you have to tweak your frequencies.

Instead of playing with the CRTC registers, you may want to consider playing with the dot clock PLL. Some weird things may happen if you change CRTC values. With a heatsink (a one inch thermalloy sold at digikey), the temperature did not go over 51 C.