Re: Color STN LCD controller

Anders Hellerup Madsen wrote:
> Hi,
>
> I'm trying to design a controller for a Hitachi color STN display, but 
> I'm running in to all kinds of problems here. I think most of it comes 
> from the fact that I really don't know anything about how LCD displays 
> work, so I was hoping someone in this group could enlighten me a little.
>
>  From what I've gathered from the displays datasheet, it seems the 
> display is controlled by two different clock signals, one for vertical 
> and one for horizontal lines. Once these clock signals are set 
> correctly, it should just be a matter of clocking the pixel data in right?

kinda, you would normally have something like a clk to clock in the 
pixels, a sync for each line and a sync for each frame.

> There seems to be three bits for each color component, red, blue and 
> green, and by my calculation this gives 8 different colors. However the 
> display is listed as beeing able to show up to 65,000 different colors. 
> How exactly is this possible?

shouldn't that be, ... 8*8*8 = 512 colors

> I have thought about various dithering schemes, but i think most of them 
> implies very dramatical losses in refresh speeds, resolution and image 
> quality. What is the normal way of producing colors on a CSTN display?
>
> Regards, Anders

if you stick to some form of toggling between different intensities of
each color to get apparent intensities in between, shouldn't only the 
resulting refresh rate go down?

-Lasse