On May 13, 2008, at 2:29 AM, Dietmar Stölting wrote:
Hi all, after readinghttp://www.whyxo.com/2008/01/08/external-monitor-or-projector-for- the-xo/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
http://wiki.laptop.org/go/Remote_displayYou are not the first to think of this, nor will you be the first to try it.
We don't recommend it. wad ----------------------------------------- [Additional information you will need if you choose to proceed] Components that were depopulated on C2 (MP machines) needed to support VGA output are: U2, U3: 74AHCT1G125GW (sync drivers) C152: 0.1 uF R1, R2, R3: 75 ohm To support the VGA I2C link (UART 2 on the CS5536 southbridge): R122, R123: 10K Q7, Q8: 2N7002 R115, R116: 10KD6: CH501H-40PT (just about any schottky diode should do, this is inline
in the +5V supplied to the monitor)
Good luck finding that VGA connector, I don't have a part number for it.
The pinout is attached.
The signal/pin mapping is:
Red - 1
Green - 2
Blue - 3
NC - 4,11
GND - 5,6,7,8,10
VSYNC - 14
HSYNC - 13
EDID_DATA - 12
EDID_CLK - 15
VGA Pinout.pdf
Description: Adobe PDF document
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