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Topic: newbie having problems with 4bit LCD (4x20) (Read 1 time) previous topic - next topic

netnews

Problem
row #1 & #3 have all 20 char boxes illuminated
row #2 & #4 have all 20 blank

My setup
Arduino v0007
Display HD44780 20X4 Character LCD Display with BLUE backlight
http://cgi.ebay.com/HD44780-20X4-Character-LCD-Display-with-BLUE-backlight_W0QQitemZ270096989566QQcategoryZ26206QQrdZ1QQcmdZViewItem

i  followed
Library & example http://www.arduino.cc/playground/Code/LCD4BitLibrary
Wiring http://www.arduino.cc/playground/uploads/ScematicLcd/scematic_lcd.pdf

I tried
-w & w/o RW low
-USING_RW is true or false.
-checked wiring 3x
-LCD4Bit lcd = LCD4Bit(1); & LCD4Bit lcd = LCD4Bit(4); (also uncommented "2nd line")

lep136

#1
Oct 01, 2009, 04:31 am Last Edit: Oct 01, 2009, 04:57 am by lep136 Reason: 1
SUGESTION!!! use a potentiometer from pin 3 to ground.  This is the contrast display.  It took me 5 hours to find out that you have to use a potentiometer to edit the contrast otherwise you will not see anyting on the lcd.  Just the backlit.   Also, I got to see bargled symbols sent to the lcd, but I have not been able to send actual messages to it..

let mek now if you have any success.  My email is monstertech5000@gmail.com
thanx

so far I downloaded the LCD4Bit library and added it to both \hardware\libraries\LCD4Bit


please help.
:-/
Leo

floresta

lep136:
Quote
Problem
row #1 & #3 have all 20 char boxes illuminated
row #2 & #4 have all 20 blank

This is normal for a display that has power applied but has not been initialized properly.

Quote
so far I downloaded the LCD4Bit library ...

The original post is 2-1/2 years old and so is the library you mentioned.  Try using the latest version of the LiquidCrystal library (Arduino v0017) and see if things work out better.

Don



lep136

I see... I used a potentiometer to edit the contrast and also grounded the RW pin.. I have not edited the library code to false.. i'm not sure if I have to do that.  but I see all kinds of symbols scrolling through the lcd.  

I think i might be send it incorrect  commands.

I have the following

LCD pin       Arduino pin
1                 ground
2                 5v
3                 potentionmeter to ground
4                 12
5                  ground
6                 3
11               7
12               8
13               9
14               10
15               14
16               ground

this worked for us.

the library we used was LCD4Bit 4X40  even though we have a 4X20 8-) 8-) 8-) 8-) 8-)


frostin

You need to have this on the POT:

[|||||||||||||||||||||||||||||]
  [||||]     [||||]    [||||]
   +5v      pin 3     Ground

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