AVR-Chat

David Kelly wrote:
> On Feb 15, 2007, at 3:59 PM, kernels_nz wrote:
>> Many may have suggested this to you, but your display is probably
>> working fine, just way too much contrast. Made the same mistake when
>> I used my first LCD module many years ago. Put a 10k pot between Vcc
>> and GND with the output going to the contrast pin, and adjust until
>> you see text. Contrast pin is usually pin #3 on most LCD modules.
> 

> IIRC when top line is dark and bottom is not the controller has not
> been initialized. 
> 
> If it was only a matter of contrast then both top and bottom would be
> equally dark. 
> 
> When the Hitachi controller powers up it drives all the pixels in the
> top line until its initialized in the 2 line mode. 


This is true - it's not a fault, just means your software has not
initialised the display.

The controllers on the LCDs are really really slow compared to AVR
speed. If your LCD initialisation is not working, try putting wait loops
in everywhere - you have to wait several milliseconds for the controller
to initialise properly.


-- 
Tim Mitchell
tim@sabretechnology.co.uk http://www.sabretechnology.co.uk
Sabre Technology (Hull) Ltd, 3a Newlands Science Park, Hull HU6 7TQ
t:01482 801003 f:01482 801078

I have programmed LCD's many times and use a 10ms delay between each setup command.

www.ckp-railways.talktalk.net/pcbcad21.htm




Tim Mitchell <tim@sabretechnology.co.uk> wrote:                                  David Kelly wrote:
 > On Feb 15, 2007, at 3:59 PM, kernels_nz wrote:
 >> Many may have suggested this to you, but your display is probably
 >> working fine, just way too much contrast. Made the same mistake when
 >> I used my first LCD module many years ago. Put a 10k pot between Vcc
 >> and GND with the output going to the contrast pin, and adjust until
 >> you see text. Contrast pin is usually pin #3 on most LCD modules.
 > 
 
 > IIRC when top line is dark and bottom is not the controller has not
 > been initialized. 
 > 
 > If it was only a matter of contrast then both top and bottom would be
 > equally dark. 
 > 
 > When the Hitachi controller powers up it drives all the pixels in the
 > top line until its initialized in the 2 line mode. 
 
 This is true - it's not a fault, just means your software has not
 initialised the display.
 
 The controllers on the LCDs are really really slow compared to AVR
 speed. If your LCD initialisation is not working, try putting wait loops
 in everywhere - you have to wait several milliseconds for the controller
 to initialise properly.
 
 -- 
 Tim Mitchell
 tim@sabretechnology.co.uk http://www.sabretechnology.co.uk
 Sabre Technology (Hull) Ltd, 3a Newlands Science Park, Hull HU6 7TQ
 t:01482 801003 f:01482 801078
 
     
                       

 		
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On Fri, Feb 16, 2007 at 11:53:22AM -0000, Tim Mitchell wrote:
> 
> This is true - it's not a fault, just means your software has not
> initialised the display.
> 
> The controllers on the LCDs are really really slow compared to AVR
> speed. If your LCD initialisation is not working, try putting wait
> loops in everywhere - you have to wait several milliseconds for the
> controller to initialise properly.

Most don't do it but I have always advocated polling the busy bit on the
LCD controller rather than use timing loops.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.