[Gc-linux-devel] Video modes on Gamecube

[Rob R. <ro...@re...>]

Hi all,

I'm trying to see if it is possible to hoop up a TFT LCD (from an old 
laptop) to the gamecube digital video output. The output seems to be 
reasonably compatible with the timing required for the TFT.
What I have found in patent 6609977 
(http://freepatentsonline.com/6609977.html, search for Example Video 
Interface)
The digital output outputs Y, Cr, Y ,Cb data on a fixed rate of 27 MHz 
and the output format is selectable between NTSC, PAL, MPAL(?) and Debug 
(CCIR656). The 27MHz makes sense for about 640 pixels horizontally for 
interlaced video. TFT displays however require non-interlaced data. To 
avoid using a difficult conversion, it is nescessary to use a 54MHz 
pixel clock, which should be possible according to the patent:

 VI Clock Select Register (R/W)
    This register selects whether the VI will receive a 27 Mhz or a 54 Mhz
    clock. The 54 Mhz clock is used only with the progressive
                          display modes.
        VICLKSEL          1       0 -27 Mhz video clk      0
                                  1 -54 Mhz video clk


Is it possible with the current gcnfb module to select other modes than 
PAL or NTSC? Or is there an other way to
tweak around with the video registers?

This interlaced/non-interlaced issue seems to be the only problem in 
interfacing TFT LCD's to the GC, since the timing is quite compatible on 
all other cases and interfacing should be a matter of a simple CPLD to 
split the data stream, extract sync data and convert it to RGB.

Kind regards,

Rob