Hello,
I recently found an old Sharp LM32019T 320x240 LCD display and started experimenting with it. I'm currently trying to get it to show a very basic test pattern using a PIC16F690 microcontroller. So far the results are mixed - it does show the test pattern sometimes, but most often the display either remains blank, or shows a while rectangle on the top 1/3 of the screen, or shows the pattern only in the top 1/3.
One very strange thing that I noticed is that if I detach the DISP_OFF pin and hold the wire in my hand it mostly shows the whole test pattern, but if I set it to logical 1, or logical 0, it most often remains blank.
This made me think that I got the pin numbers wrong - I started to think that what I thought is the DISP_OFF pin is in fact some the data pulse or row latch signal. But this doesn't explain how sometimes the pattern is shown correctly with DISP_OFF set to 1...
Another thing is that it seems what the display shows depends on the LCD drive voltage - when the voltage is higher the display pattern is more likely to show properly; when the drive voltage is lower, the pattern may completely disappear. My limited understanding is that what the LCD drive voltage should mostly affect the display contrast, but not the pattern itself - is this correct?
I'm trying now to rule out power supply problems - nose, things like that. Of course, the display itself might be faulty... Anything else I should check or try? What would you do in my place?
Thanks,
- Alex