4x20lcd

Newzed · 2007-07-30 00:15

I am running a program in my Proto board for a 2x16 LCD.· I am using a· 4x20 LCD and the display works fine using the two top lines of the 4x20.· I have tried without success to modify the program so that I can use all four lines of my LCD.· I have attached the program, plus the object it uses.· Can someone please show me how to convert the 2x16 to a 4x20.· BTW, even though the program is for a 2x16, I am able to use 20 characters with the program as it stands.

Thanks

Sid

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mcstar · 2007-09-09 21:31

Were you ever able to figure out this issue? I've been working on the same problem for a couple days now. Sending the display to the correct address does not seem to help. Any ideas?

deSilva · 2007-09-09 21:40

You most likely have to adjust the addresses, they differ of course for 16 and 40 displays, as the latter have 2 controllers

        16x Module   20x4 Module
        also 40x
Line 1  00h - 0Fh    00h - 13h
Line 2  40h - 4Fh    40h - 53h
Line 3  10h - 1Fh    14h - 27h
Line 4  50h - 5fh    54h - 67h

Post Edited (deSilva) : 9/9/2007 9:50:15 PM GMT

deSilva · 2007-09-09 21:58

P.S.: This is from my driver, note lines and columns are zero-based here:

PUB GotoXY(Column, Row)| CRowOffset
  CRowOffset := lookupz(Row: $80, $C0, $94, $D4) 'for 4x20
  DataOut(column|CRowOffset)

boeboy · 2007-09-09 22:04

Check here http://obex.parallax.com/objects/104/·hope this helps.

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My computer, http://forums.parallax.com/showthread.php?p=630466

mcstar · 2007-09-10 03:46

Thanks! I was able to trace the issue down to insufficient power. The text was there, it was just so dim I coudn't see it. It was decieving however because whenever the display was in 1-Line mode, everything was bright as could be. When I went to 2-line mode, my batteries couldn't source enough current to maintain the voltage the display needed. I've learned that the four line display cannot be succesfully driven in 2-line mode from a 3.2volt source. Also, if your nicad batteries are only providing <4 volts, you can forget it also. I've also added POTs to both the contrast and LEDs, very important. So, mine was not a programming problem, but an electrical engineering one. Thanks for the input!

4x20lcd

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