Hey guys, I've been trying to do some research. I have a Hitachi
TX26D11VM1CAA panel, which is 800x256 resolution.
It has a 40 pin interface, which is from what I finally found out by
getting the data sheet directly from Hitachi, as a C-MOS 18bit
interface (6 bits per color).
It seems that a few of you have successfully been able to drive
similar LCDs off the Beagleboard J4/J5 headers, however after reading
the BB breakout on the J4/J5 pinouts, I notice that nothing is
specified as for colors/etc. I am assuming all of this has to be
programmed in some type of Linux display driver?
The 40 pin header on the LCD is:
1 VSS - GND
2 VSS - GND
3 DCLK - Dot Clock
4 VSS - GND
5 VSS - GND
6 Ic (Not used)
7 R0 - Red
8 R1 - Red
9 R2 - Red
10 VSS - GND
11 R3 - Red
12 R4 - Red
13 R5 - Red
14 VSS - GND
15 G0 - Green
16 G1 - Green
17 G2 - Green
18 VSS - GND
19 G3 - Green
20 G4 - Green
21 G5 - Green
22 VSS - GND
23 B0 - Blue
24 B1 - Blue
25 B2 - Blue
26 VSS - GND
27 B3 - Blue
28 B4 - Blue
29 B5 - Blue
30 VSS - GND
31 IC (Not Used)
32 VSS - GND
33 NC (Not Used)
34 VSS - GND
35 DTMG - Display Timing
36 NC (Not Used)
37 VDD - 3.3v
38 VDD - 3.3v
39 VDD - 3.3v
40 VDD - 3.3v
Obviously there are a ton of grounds on this connection. I am also
assuming the data bits need to be 3.3v, and the Beagleboard outputs
1.8v? If so a level shift will need to be brought in?
Any help to get this panel working on the Beagleboard would be
greatly, greatly appreciated.
You will absolutley need a level shifter to take the 1.8V to whatever level the panel requires. The datasheet for the panel specifies the colors and the schematic of the Beagle has the clors labeled on it as well. ANd yes, you wll indeed need a driver to set the timings of the LCD signals to match those required by the LCD panel.
The level shift should not be a problem. I will go over the
Beagleboard data sheet again, IIRC all I saw was DVI_DATA## with 'LCD
Pixel Data Bit'. No listing of which color is what.
Also, which would I tie to the dot clock and the display timer?
Writing a driver could get interesting, but I will do some research on
how to write one.
The schematic shows what signals are what colors. As to the driver, there is already support for the adjustment of the resolution and timing of the display output from Beagle, but if you need back light control, special power sequencing, touchscreen support, etc. then that will require some work.
From a quick glance it seems to me that the V/H sync signals provided by the OMAP’s DSS are different from what the display expects. I am not familiar with this display but at least on paper the DTMG signal differs from normal VSYNC/HSYNC + OE that OMAP provides.
The polarity of V/H can be changed via SW, in the driver. Feel free to read the proceccor’s Technical Reference Manual for more information on how to do this…
One further comment to this. In order to be able to drive the DTMG signal the user might need to connect it to the DE signal of the OMAP as opposed to the H/V-Sync signals. That being said. The DE-signals is as well configurable and thereby shouldn’t cause any problem…