Re: does geode GX1 support 480x234 resolution ?

From: Andrew Worsley (Andrew.Worsley_at_nospam.4.me)
Date: 02/01/05 

Date: Tue, 1 Feb 2005 17:10:38 +1300

We use a Sharp LQ070T5CRQ1, which sounds very similar spec'd to your LCD
(same resolution, clock rate etc). We no longer drive this from a Geode
CPU (our design now uses an SH4), but we did once have this working with
a National Semiconductor "Pompano" board, which had an SC1200 processor
I beleive). We were also using the CRT output, and had many doubts that
it could be made to work, since it was a non-standard resolution
according to the SC1200 data***.

We have long since ditched the code, but I did find an email that had a
snippet with the all-important timing parameters. Maybe they will be of
use to you...

DWORD hSkewOffset = 7;
DWORD hSkew[] = {
                                        0x00000000,
                                        0x00004000,
                                        0x00008000,
                                        0x0000C000,
                                        0x00010000,
                                        0x00014000,
                                        0x00018000,
                                        0x0001C000 };

// skew should be 0x0001C000 1/10/2002

DISPLAYMODE saveMode;
DISPLAYMODE sharpDisplayMode =
{ GFX_MODE_60HZ |
        /* refresh rate = 60 */
  GFX_MODE_8BPP | GFX_MODE_16BPP | /* 8 and 16
BPP valid */
  GFX_MODE_NEG_HSYNC | GFX_MODE_NEG_VSYNC, /* negative
syncs */
                                                
        0x01E0, //hactive 0x01E0
        0x01F0, //hblankstart; 0x01F0
        0x01F8, //hsyncstart; 0x01F8
        0x0228, //hsyncend; 0x0228
        0x0258, //hblankend; 0x0258
        0x0260, //htotal; 0x0260
        /* horizontal timings */
//sorta works 0x01E1, 0x01F0, 0x01F0, 0x01F4, 0x0218, 0x0220, /*
horizontal timings */
// 0x0280, 0x0288, 0x0290, 0x02E8, 0x0318, 0x0320, /* horizontal
timings */

        0xEA, //vactive; 0xEA,
        0xEA, //vblankstart; 0xEA,
        0xF3, //vsyncstart; 0xF2,
        0xF6, //vsyncend; 0xF5,
        0x106, //vblankend; 0x106,
        0x106, //vtotal; 0x106,
        /* vertical timings */
// 0x01E0, 0x01E8, 0x01EA, 0x01EC, 0x0205, 0x020D, /* vertical timings
*/
        0x00192CCC,
                
};

Good luck!!!

Andrew