[uCsimm] lcd timing registers

From: Filip Peters (filip.peters@metris.be)
Date: Thu Jan 06 2000 - 08:37:44 EST


Hello all,

I'm trying to connect a qvga display to the ucsimm but I'm having still
some troubles, the hardware interface seems ok, but i'm not sure if I
have the correct values for the lcd registers.

I'm using a 320x240 lcd screen (epson ECMA0635-2 , very cheap at around
35$) which has a 4bit interface, wants a 125ns lcd clock and around 13ms
frame period (= 76Hz refresh), as most 1/4 vga screens.

What's most confusing is the formula for the framerate, what is the
value for the clk used in this formula on a normal ucsimm, is it 62.5 or
125ns?

I found out that the initialization in the kernel turns the lcd
interface back off (so it doesn't matter what you enter for environment
variables once you load the kernel), and configuring the kernel for
framebuffersupport gives a framebuffer that is hardcoded to 160x160. So
I'll have to take a long look at that code if I'm going to use the
kernel framebuffer.
For now I'm using setenv for initializing the screen and have commented
the line that turned of the lcd circuit in the kernel.

Overall, I must say I find the ucsimm a very good product, flashing a
new kernel is very easy when you have nfs'd a directory, and the
handbook is excellent on getting you started. If only I could get this
lcd screen to work <sigh>.

Are there other people who have connected a different screen than the
640x480 lcd screen to their ucsimm? How did you set it up? I would
really like to hear from you!

Filip.

--
Ir. Filip Peters
fp@metris.be

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