VGA external on OLPC

Jim Gettys jg at
Tue May 13 09:30:03 EDT 2008

Note there are USB display adapters (I have one in my hand as I write
this); I'd love to see someone working on drivers for it.  There
may even be some code kicking around that just needs TLC (though it's
been long enough I'd have to dig up my contacts and check). 

If there is anyone interested out there, let me know.
                      - Jim

On Tue, 2008-05-13 at 08:29 +0200, Dietmar Stölting wrote:
> Hi all, after reading
> I am sure, that it is possible to integrate a VGA external connector
> for the OLPC. On the Prototype-A motherboard layout there was such an
> external VGA connector, but on G1G1 version it is gone.
> I am a teacher and it would be very good for projection with a beamer
> or if your LCD is broken, to have such an external VGA connector. 
> My problem is, that I have no schematic or a good photo of both sides
> of the Prototype-A motherboard. You can read in the Geode LX databook,
> that the Geode LX chip offers direct VGA support and connection. But
> some parts of the Prototype-A motherboard have gone in G1G1 version
> and so I cannot see, which direct lines from the processor has to be
> used for the direct VGA support. Pin 1,2,3 are used for the RGB signal
> on the G1G1 layout, and pin 13 seems to be Hsync and pin 14 Vsync. I
> do not know, what is the use of pin 4,9,12,15, because they are also
> wired on the G1G1 version.
> Pin 5, 6,7,8,10,11 are not connected on the G1G1 version and I think,
> that this was the same for the Prototype-A motherboard layout. But
> still there must be the lines direct to the Geode processor from the
> Prototype-A layout. They only have to be found (recogniced) via a good
> photo of the Prototype-A layout (both sides). Please send me your
> photos and rtell me, what you think about my idea,
> Dietmar
> PS: RGB lines of VGA ends on G1G1 layout direct in font of C51, C41,
> C86. If this is true, only Vsync and Hsync have to be found.
> Wikipedia says about the pins for VGA:
> Pin 1 RED Red video 
> Pin 2 GREEN Green video 
> Pin 3 BLUE Blue video 
> Pin 4 N/C Not connected 
> Pin 5 GND Ground (HSync) 
> Pin 6 RED_RTN Red return 
> Pin 7 GREEN_RTN Green return 
> Pin 8 BLUE_RTN Blue return 
> Pin 9 +5 V +5 V (DDC) 
> Pin 10 GND Ground (VSync, DDC) 
> Pin 11 N/C Not connected 
> Pin 12 SDA I²C data 
> Pin 13 HSync Horizontal sync 
> Pin 14 VSync Vertical sync 
> Pin 15 SCL I²C clock 
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Jim Gettys <jg at>
One Laptop Per Child

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