Displaytech Problem

Discussion in 'General Electronics Chat' started by geoffers, Oct 25, 2012.

  1. geoffers

    Thread Starter Active Member

    Oct 25, 2010
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    Hi all,
    Has anyone else had any problems with displaytech lcd's? I've used quite a few of them in different things without any problems. Got a 16x1 display for my current project and can only get the first 8 characters to work?? I've used 16x2's and a large character 16x1 before with the same setup (pic18f2523 4 bit interface) I've played about with the initalization code but it still won't play the game! It was cheap(£5!) should I just send it back?
    Cheers Geoff
     
  2. takao21203

    Distinguished Member

    Apr 28, 2012
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    Did you write the LCD code yourself? Addressing etc.? The PIC model is really secondary. The code you use matters. If you use a library, some displays of course will not fully work.
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I've seen some displays where the memory for one long line is in two different areas. Meaning you start at address 0x80 and expect the 8th character to be at 0x88 but it's really at 0xC0 or something, so read the data sheet again till you see where... or just keep writing characters till something shows.
     
  4. Sensacell

    Well-Known Member

    Jun 19, 2012
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    Yep, study the data sheet carefully.

    The initializations and memory mapping vary and are very hard to decipher.
    Chances are if you are talking to it at all, it's working, you just need to figure out how to address the remaining display area.
     
  5. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    One of the most common difficulties which would not happen if you RTFM.
    (Been there...);)
     
  6. geoffers

    Thread Starter Active Member

    Oct 25, 2010
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    6
    Thamks for the quick replies, I've played around a bit, I wrote a loop continuosly sending one character, the first 8 appear, then theres a little pause and the next 8 appear. The mapping starts at 00h for the first 8 then 40h for the second which seems a bit strange? I would have thought incrementing the cursor should deal with the change? I tried writing a character to 40h and nothing happens. I will have another look at the data sheet, not getting stuff to work irratates me a bit but I might just change the display it was working fine before!
    Cheers Geoff
     
  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Had you read the datasheet first it would be not strange at all. Just counter intuitive.

    With the MAX7219 (a nice LEDs driver) I made the mistake of taking for granted that the control bytes (words?) for a certain mode would follow a logical binary sequence. By RTFM, I learnt they did not.

    Good luck!
     
  8. geoffers

    Thread Starter Active Member

    Oct 25, 2010
    239
    6
    Hi,
    Thanks, I had read that before my first post. I should have mentioned it, I would have thought that the cursor increment function should deal with that though? If thats not the case then I will probably just change to a different display, my programme is already quite long and uses the lcd alot. Showing my ignorance whats RTFM?
    Cheers Geoff
     
  9. geoffers

    Thread Starter Active Member

    Oct 25, 2010
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    Ahh I see! If anyones curious google it like I did.
     
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