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need HELP 320x240 Graphic LCD + SED1335 screen goes blanck
http://forum.lcdinfo.com/viewtopic.php?f=9&t=1090		 Page 1 of 1
Author:  merqutio69 [ Sat Mar 05, 2005 5:37 ]
Post subject:  need HELP 320x240 Graphic LCD + SED1335 screen goes blanck
I have a graphic LCD, for which I wrote C code for initialization and to display a few characters, I'm using the SED1335 display chip.
The screen shows up the proper output randomly: sometimes it works fine, then I unplug it and plug it back again and the screen goes all black or it starts flickering.

There might be some timing issues with the power or maybe with the initialization. Can someone with a little of bit of experience take a look at it??

I posted my code and the datasheet for you to take a look here:

http://stw.ryerson.ca/~soduneye/


Thanks
Author:  Henri [ Mon Mar 07, 2005 23:24 ]
Post subject: 
You might want to try adjusting the TCR value in initialization. I remember reading in some Epson documents that bad TCR value can cause unstability with the display.

Also how do you have the reset signal connected ? Noise in that might cause some strange behaviour.
Author:  merqutio69 [ Tue Mar 08, 2005 8:51 ]
Post subject: 
I have calculated and double checked the TCR value many times. As long as TCR satisfies [TC/R] > [C/R] + 4, according to the data sheet then it's ok.

Yes the reset signal is connected, and is active low so I have set to logic 1.

I'm starting to think that my problem might have to do with timing of the power supply.

Have you ever played with a graphic LCD? If so what kind of problems did u find?
Author:  Syridian [ Tue Mar 08, 2005 23:57 ]
Post subject: 
What have you connected the reset to? Do you use a pull-up resistor on it? If you don't, you might concider it.

You said the reset is set to logic 1... This implies it's connected to something that can be controlled.. Is this right? Is there any way that this might periodically drop, causing an inproper reset operation (ie; Not held low for long enough to initiate a proper reset).
Author:  Henri [ Wed Mar 16, 2005 19:15 ]
Post subject: 
I just checked your link to http://stw.ryerson.ca/~soduneye/ again and I see an interesting project there. :)

Were you able to figure out what the problem with your lcd was ? If so would be nice to know the solution for future reference.

I once had some problems with S1D13305 when I wasn't giving it a good reset signal from the microcontroller in the start. I don't know if it had anything to do with the fact that the controller board was just behind a QVGA Planar EL display with longer than necessary cable and also otherwise maybe not so clean environment as it was an user interface module for vehicle use (with CAN interface too btw ;) ).
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