DVI-VGA converter from beagleboard toys


I am working with ubuntu 9.04 for beagleboard, and i need video for a vga monitor, so i get a converter from beagle board toys, but the image is not rigth, the colors are switch and the image is much bigger then the monitor.

ithink it could be U-boot. i have 2009.06-rc2 version.

I need some help.

Best Regards

I suggest you re ask the queston based on the resolution and timings that your monitor requires. All the board does is to convert the LCD bits into the RGB VGA format. What needs to change is the timings of the signal from the OMAP3530 which requires a SW change.


Hi Jaime,

Which adapter is this? More then likely it needs a very specific
resolution & timing set in uboot and passed to the kernel.


The adapter needs no such timings per se. It connects to the LCD pins and creates a VGA output by providing the D/A drivers and the clock signals… It has nothing at all to do with the DVI-D output of the TFP410. The timings that it requires is based on what timings the monitor that it is connected to requires.


thanks for your help, i tried on 4 diferents dell monitors, but the problem is the same, i am working with omapfb.mode=dvi:1440x900MR16@60 and also tried dvi:1280x720MR-16@60,but nothing. recently i tried Angstrom, for the board validation and aparently it works fine, do you know how to modify the timing parameters in u-boot?

best regards

Jaime Silva

2009/12/2 Gerald Coley <gerald@beagleboard.org>

One problem is that the available screen resolutions are set for HDTV
format LCD monitors.

I would imagine that the DVI interface influenced this...

- dan

I think that’s right, but wath can i do for change these settings?
I need to compile u-boot or i do in the OS?, and can i use Openembedded?


2009/12/3 Dan Poirot <dtpoirot@gmail.com>


I have been worked on the timing signals of omapfb driver, and get a nice image when kernel boots up, but when the desktop init the thinks gone bad, and the problem is the same.
Do I have to build my own FS, or rebuild the kernel?, i am using the kernel without DSS2, but the filesystem have been build with the command line:

sudo ./rootstock --fqdn --login --password --imagesize --seed --dist <jaunty/karmic> --serial --kernel-image

P.S. Sorry for my english.


2009/12/3 Jaime Silva <ing.jaimesilva@gmail.com>

Dear Jaime,

How did You do work on the timing signals of omapfb driver? I am also
working on same trouble. can you please help me?




I did it with the source from git


and Codesourcery.

in the file /drivers/video/omap/omapfb_main.c is the main struct for the video signals:

struct lcd_panel omap3beagle_panel = {

.name = “omap3beagle”,

.bpp = 16,
.data_lines = 24,
.x_res = LCD_XRES, /* =1024 /
.y_res = LCD_YRES, /
=768 /
.hsw = 3, /
hsync_len (4) - 1 /
.hfp = 3, /
right_margin (4) - 1 /
.hbp = 39, /
left_margin (40) - 1 /
.vsw = 1, /
vsync_len (2) - 1 /
.vfp = 2, /
lower_margin /
.vbp = 7, /
upper_margin (8) - 1 */

.pixel_clock = LCD_PIXCLOCK, /* =64000 */

and there modify the signlas that you need, aditional in the function set_lcd_timmings in the file dispc.c are the limits for each parameter.

then you just compile with Codesourcery (the one that i use)

I hope thats what you need.


2010/2/15 Selim ÖLÇER <olcerselim@gmail.com>


Thank you for your help. I have a few question. Can I write any
resolution here? I want to change resolution to 848x480. how can I
calculate parameters?




The limits for the resolution and timing signals are in teh file dispc.c, you can calculate those parameters with the VESA timing diagrams and your monitor specification.
on Internet you can find this information.

Best regards.

2010/2/16 Selim ÖLÇER <olcerselim@gmail.com>