Beagleboard Xm Screen Resolution

Hi all !

I just received my BeagleBoard-Xm. I successfully created the SD Card from my OpenPandora running Risc Os.

I have a full hd monitor. I know that the bbmx can display only 1400×1050. Nevertheless, I expect to be able to display 1366×768. But currently, in the screen configuration dialog, when selecting “Generic” ’ this resolution 1366 × 768 is not en the list. so, my question is how can I access this resolution ?

Secondly, at each reboot, the BBMX returns to the lowest resolution. How can I make my choice persistent ?

Thank you for your help.

François

when selecting “Generic” ’ this resolution 1366 × 768 is not en the list. so, my question is how can I access this resolution ?

I think the answer there is Either pick an MDF that contains that resolution or add that resolution to the Generic MDF

Secondly, at each reboot, the BBMX returns to the lowest resolution. How can I make my choice persistent ?

Ah, now that appears to be the old chestnut of a vertical bar character being entered to comment out the resloution line in !Boot.Choices.Predesk.Configure.Monitor

Change it so that the line reads WimpMode X1024 Y768 C256 F50 and you get a 1024 × 768 256 colours 50Hz frame rate
Or change it using the configure options.

AND THEN lock the file as read only.

Save all settings and reboot.

Somebody somewhere thinks its a good idea to have the system reset to minimal defaults at the most minimal prompting.

Also, you have settle to either 1360 or 1368 × 768 as, if I remember correctly, the horizontal resolution is required to be a multiple of 8.

Try these:

#1360 × 768 (58Hz)
startmode
mode_name:1360 × 768
x_res:1360
y_res:768
pixel_rate:86000
h_timings:32,100,14,1360,0,98
v_timings:5,16,0,768,0,0
sync_pol:2
endmode

# 1360 × 768 (60Hz)
startmode
mode_name:1360 × 768
x_res:1360
y_res:768
pixel_rate:78115
h_timings:48,80,32,1360,58,70
v_timings:5,14,0,768,0,3
sync_pol:2
endmode

Not sure if they work with the Beagleboard though. You can get higher resolutions btw. I run my BB-xM’s monitor at 1920×1080 but it’s a TV/Monitor suitable for lower frequencies. ISTR running my previous one at 1400×900 or something like that. Depends on the model of course.

Hello

Thank you for your answers.
For the resolution of 1360×768, it is now working. But there is some “twinkling” (i am not sure this is the right word in english) that is very uncomfortable and give headaches after some time. I suppose, I should modify the parameters like pixel_rate and so on, but I have no idea what values I should put.
My screen isa Samsung SyncMaster S22B350T.

For the peristence, unfortunately, this does not work. Actually, nothing was commented in this Monitor file and yet the resolution come back to the lowest at each reboot.

I look at the documentation of my screen and have found the following:

Resolution;Horiz Freq;Vert Freq;Clock;H/V
VESA 1280×720;45000;60000;74250;/
VESA 1280×800;49702;59810;83500;-/+
VESA 1280×1024;63981;60020;108000;/
VESA 1280×1024;79976;75025;135000;/
VESA 1440×900;55935;59887;106500;-/+
VESA 1680×1050;65290;59954;146250;-/+
VESA 1920×1080;67500;60000;148500;/

Thank you for your help.

For the peristence, unfortunately, this does not work. Actually, nothing was commented in this Monitor file and yet the resolution come back to the lowest at each reboot.

I’m assuming you’re using !configure and not the iconbar icon to set your resolution. Did you remember to menu click and save cmos after setting your resolution?

Hello Patric

Even after saving the CMOS, my choice for screen resolution is not persistent.
Note that my choice for keyboard layout IS persistent…

Regards

Hello Patric

I just find out that the CMOS file was not written on the SDCard direcly, but in .!Boot.Choices
After I copied the CMOS on the SDCard, indeed, the resolution became persistent after reboot.
SO, this problem is solved.Now, I would like, based on the specs above, write the most appropriate MDF file for my Screen in order to have the most conformtable experience.
Is anyone could help on this? How can I determine the parameters to write?

Thanks a lot for your help.

Regards

Hi François,

If you look at the Pandora-MDF-Folder you will find my Acer HQ MDF. One for all… xM, Panda, a9home ;-)
The 1440 × 900 is working with my xM.

I found that although the monitor was 1366 × 768 neither my PC nor RISC OS would drive at that mode, I found that 1360 * 768 worked though on my beagleboard.

I suggest you try dropping the extra 6 pixels

I found that although the monitor was 1366 × 768 neither my PC nor RISC OS would drive at that mode, I found that 1360 * 768 worked though on my beagleboard.

1366×768 is the logical widescreen (16:9) version of 1024×768; however as you noticed, some video hardware has “specific requirements” such as the pixel dimensions being divisible by eight. As such, 1360×768 is the best you’ll be able to do.

This does, incidentally, raise an interesting question → why do we seem happy to display HD content (generally 1280×720) on displays with 1366×768 pixels? The real reason is probably to do with TV manufacturers recycling tech for computer monitors, but it does make you wonder how the rescaling effects the quality of the picture. I guess this is the cue for Jim Lesurf and Dave Higton to enter the conversation, because I have a funny feeling that the stuff they’re discussing regarding audio is exactly the same here, only in a visual sense; and I just can’t seem to imagine that 1280×720 will upscale to 1366×768 nicely.
And… By nicely I mean aspiring to something better than my DVD player that plays NTSC discs on PAL equipment by playing five frames at PAL speed and discarding the sixth frame. You really don’t want to know what that does to pans and motion. There are better ways, but I rather suspect domestic equipment will aim for the cheap option, not the good option. Which brings us right back to bending an HD picture to be 6.66(recurring)% larger.

Hello Raik

Could you post your MDF for resolution 1440×900?
I have tried playing with !MakeModes to approach the following standard signal mode described in my monitor’s manual without success…
VESA 1440×900;55935;59887;106500;-/+
Anything approaching never displays in the list of available resolution in the Configure/Screen dialog.

Thanks for your help.

Regards

François

I guess this is the cue for Jim Lesurf and Dave Higton to enter the conversation, because I have a funny feeling that the stuff they’re discussing regarding audio is exactly the same here, only in a visual sense

I don’t consider myself competent in video. A lot of what we are interested in, in audio, is in the frequency domain. Video isn’t.

Hi François,

Yes ;-)

# 1440 × 900 (55Hz)
startmode
mode_name:1440 × 900
x_res:1440
y_res:900
pixel_rate:86500
h_timings:32,100,14,1440,0,98
v_timings:5,16,0,900,0,0
sync_pol:2
endmode

I hope that helps

Hi,

Does anybody have a definition for 1280×1024 that ought not cause compatibility issues with a HDMI→VGA adaptor? [in other words, preferably equivalent to a DMT mode, 60Hz or 75Hz¹ if possible]

Thanks.

¹ 1280×1024@75Hz is what the Pi outputs. Everything is happy with that. I’m not sure if the OMAP3/xM is up to that sort of pixel clocking though…

I have this one

# 1280×1024@60Hz
startmode
mode_name:1280 × 1024
x_res:1280
y_res:1024
pixel_rate:86500
h_timings:32,80,0,1280,0,48
v_timings:5,13,0,1024,0,3
sync_pol:3
endmode

But not sure if this 60Hz or near 60Hz. I can try this tomorrow morning.

Hi Raik

Thank you for your help.

I will finally stick with 1360×768 as the mode 1440×900 is twinkling too much and is very uncomfortable (and unusable for me!)…
And to be honest, I am wondering what screen I should use to have the most confortable experience, because even 1360×768 on my full hd monitor twinkles in an unpleasant way…

It is so far away of the excellent output I have with the Pi.

Cheers

François

The problem is that not all monitors working fine under 60Hz. The my Acer HQ does not flicker.
You can play a little with the parameters. Sometimes it helps. Also possible that your Beagle can handle a higher pixelrate. My Rev.B can not handle more, my Rev.C worked with 90000, if I remember correctly (I have tried 2 years ago;-)).
If you have a HD TV it ist possible that HD works with 30Hz but not all. Any monitors are also working, my Acer not. Try and error in the media market helps ;-)

Hello

Could someone help me to define the right MDF, considering the following screen details:

Resolution;Horiz Freq;Vert Freq;Clock;H/V
VESA 1280×720;45000;60000;74250;/
VESA 1280×800;49702;59810;83500;-/+
VESA 1280×1024;63981;60020;108000;/
VESA 1280×1024;79976;75025;135000;/
VESA 1440×900;55935;59887;106500;-/+
VESA 1680×1050;65290;59954;146250;-/+
VESA 1920×1080;67500;60000;148500;/

I am particularly interested in he 1440×900 resolution as it is for running on a BeagleBoard-xM, which I guess cannot reach 1680×1050 and above.

Thank you for your help.

François

I used to run my BB-Xm @ 1680×1050 on a Samsung monitor. “WimpMode X1680 Y1050 C16M F50” using an MDF from RComp’s ARMini support scheme.

The problem is that not all monitors working fine under 60Hz

Most will work okay down to 50 Hz. Much below that is less certain, although the one I’m using here is happy at 24Hz (fortunately, since the Pi can only just manage that at 4K resolution).

Hi, I recover the Armini MDF and indeed, now it works on 1440×900@60Hz.

Thank you for the help.

For future reference: Chris Gransden has ported and extended CVT http://www.riscosports.co.uk/downloads.html which allows to create VESA-compatible MDF entries. I used it successfully to produce various 4K modes for the ARMX6 and RPi.

If you can read German (or understand translations via Google Translate), I have blogged about it here: http://riscosblog.huber-net.de/2018/03/raspberry-pi-3-b-4k-und-risc-os/