VGA external on OLPC
dietmar.stoelting at t-online.de
Tue May 13 02:29:24 EDT 2008
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,
PS: RGB lines of VGA ends on G1G1 layout direct in front 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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