RE: AW: [avr-chat] LCD duty cycles, help please

[Rune Christensen]

Hello

The LCD is split into two sections upper and lower. That gives 240 lines
each and you will only be drawing one line in each section for each step.
That gives 1/240 and because of some speciel things the duty cycle is 1/242.


The VLCD is a DC voltage that is constant. Just like the 5 volt for the
circuit board. 
If you change the VLCD the contrast will change.

How often do you need to update the display? Do you need to use it to video
or only to slow graphic/text?

/Rune


> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> rg] On Behalf Of James Dessart
> Sent: Sunday, February 27, 2005 8:14 PM
> To: Flemming Gram Christensen
> Cc: address@hidden; Bob Paddock
> Subject: Re: AW: [avr-chat] LCD duty cycles, help please
> 
> 
> On Sun, 27 Feb 2005 20:02:43 +0100, Flemming Gram Christensen 
> <address@hidden> wrote:
> > ST has some application notes for the ST7 and other ST 
> > microcontrollers about driving graphic LCDs directly. It is not 
> > something you will complete in the evening.
> 
> The ST app note, unfortunately, only deals with segment-based LCDs.
> 
> > Another easier option is to use the mega169 which has the 
> hardware to 
> > drive such an display.
> 
> Same there, they only drive segments.
> 
> The module I've got is a multiplexed device (640x480), with a 
> 4-bit parallel interface and a shift-clock to move to the 
> next 4 pixels, and another to shift to the next line. There 
> is one VLCD pin for supply current, the duty cycle is 1/242 
> (which I'm still not clear on, is it 1/242 of a second, or 
> 1/242 of the time the pixel is being written
> out?) at -13.1V. I've figured out how to generate the 
> negative voltage, it's just a question of when to activate it 
> or drop it to zero, what kind of timing I need to have.
> 
> Thanks for your help.
> 
> James
> 
> 
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> AVR-chat mailing list
> address@hidden http://lists.nongnu.org/mailman/listinfo/avr-chat
> 
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