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rew
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Attaching a 320x200 display.

Tue Jun 05, 2012 7:31 am

I have a small (4") 320x200 LCD screen connected to my 'pi. (Composite).

The problem is that the console text is about 2 to 3 pixels high (surprisingly the text is sometimes readable!). And most X programs assume that I can see individual pixels. The LCD module downscales pixels it grabs from the composite video input to the pixels it displays. Is there a way that I can tell the GPU to present a 320x200 pixel screen to the software on the 'pi and then upscale that to 576x480 for composite display?

Of course having an interface between the screen and the 'pi that actually handles the 320x200 resolution would be much better. But until we get DSI to work this will have to do.
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bredman
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Re: Attaching a 320x200 display.

Tue Jun 05, 2012 8:41 am

Have a look at the wiki page http://elinux.org/RPi_config.txt

You may be able to use one of the 240p modes, and then use the overscan settings to blank out the 20 top and 20 bottom pixels.

dom
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Re: Attaching a 320x200 display.

Tue Jun 05, 2012 8:52 am

@rew
framebuffer_width=320
framebuffer_height=200

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entozoon
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Re: Attaching a 320x200 display.

Mon Jun 11, 2012 4:38 pm

Did you solve this in the end? I'm having a similar problem.
setting the framebuffer doesn't help.. because the monitor needs a higher resolution than that.
it needs to be 320x200, then upscaled to 576x480 like it was asked in the first post

dom
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Re: Attaching a 320x200 display.

Mon Jun 11, 2012 4:42 pm

entozoon wrote:it needs to be 320x200, then upscaled to 576x480 like it was asked in the first post
That's exactly what framebuffer_width/framebuffer_height does.

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entozoon
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Re: Attaching a 320x200 display.

Mon Jun 11, 2012 4:46 pm

okay, but how then do you set the target resolution?
The only way I can make it fill my small monitor is having the framebuffer set to 576x480.
Although, the monitor only actually has a resolution of 480x272.

dom
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Re: Attaching a 320x200 display.

Mon Jun 11, 2012 5:01 pm

Well the physical resolution is set by the PAL or NTSC specs and can't be changed if you want an image on the display.

You can control how big the framebuffer is before it is resized to PAL or NTSC framesize.
If it's not filling the screen then play with overscan:
http://elinux.org/R-Pi_Troubleshooting# ... D_monitors

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entozoon
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Re: Attaching a 320x200 display.

Mon Jun 11, 2012 5:13 pm

thank you,
looks like i've solved the problem by setting some beefy negative overscans

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