Lcd screen problems

[pixman]

I have a tm162acw lcd 2x16 screen

i have used nigel's tutorial 9.2 to connect the screen and hex keypad to test with.
When i start apply voltage the screen comes up blank.
I tried to adjust the contrast you can see something is there but can't read it.
After awhile the writing appears.
When you enter the code the numbers show on the second row then the screen goes
blank. I know it is not the code. I have used a 16f628a and have changed the .inc file.
I suspect that the display is faulty.
I set the lcd voltage to 0,3v as per the data sheet
any advice.

 

[Pommie]

Well, if the writing appears after a while then I suspect you're pic is running at a slow clock speed. Post your code and we may be able to help.

Mike.

 

[pixman]

I was using nigel's tutorial 9.2 code

 

[Nigel Goodwin]

I set the lcd voltage to 0,3v as per the data sheet

What do you mean by that?.

 

[pixman]

I want to test the lcd, so i used nigle's code and circuit layout.

 

[Nigel Goodwin]

Yes , but what's the 0.3V about? - did you use my exact layout or not?.

 

[pixman]

The 0,3v is what the data sheet tell's you to put on pin 3 (contrast).i have even tried your way with a pot.
I have a feeling it is the lcd itself.
When you start it the display does not all way come on straight away.
If i turn the pot up and down a few times then the display shows.
I will get a new one this afternoon and try it tonight.

 

[Nigel Goodwin]

The 0,3v is what the data sheet tell's you to put on pin 3 (contrast).i have even tried your way with a pot.

Use a pot, the contrast setting varies with temperature anyway, so it needs to be adjustable - if it could be preset to a specific voltage they wouldn't have a pin for contrast.

 

[pixman]

It was the lcd screen that was faulty.
The contrast pin had a bad connection. Clean the track a bit and soldered onto track.
All is fine.

 

[Nigel Goodwin]

It was the lcd screen that was faulty.
The contrast pin had a bad connection. Clean the track a bit and soldered onto track.
All is fine.

Nice one, it's often the silly things that catch you out.