problem with connecting 20x4 LCD to arduino

Hi, I'm new to programming and yesterday I began with LCD-s. I have a 20x4 LCD: http://www.powertipusa.com/pdf/pc2004a.pdf I connected it via the guide at http://arduino.cc/en/Tutorial/LiquidCrystal I changed in

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

the

 lcd.begin(16, 2);

to 20,4 When I powered it up it does not dispay anything. The backlight is working fine, but no text. Do I have to change anything else?

Please help me.

Thanks, Kevin.

First of all, check the connections again, and then again, and then, just in case do it again... backwards. Next the potentiometer - it's responsible for the contrast setting - check if it's wired up correctly. Alternatively try to connect the Vo (contrast pin on your LCD) to GND and see if you see anything. You should at least see all the pixels - that will mean the contrast is working fine...

I checked the connections 10 times. Everything is ok. The potentiometer was connected fine, but even with Vo connected to ground does not work. Without the backlight I can't see anything, but with backlight I can see hardly the the boxes(caracter) but they are very light grey.

The LCD library is made for HD44780 (IIRC) compatible devices. Can't find that in the the datasheet...

Have you tried to wire it up with 8 lines?

how can I wire it up with 8 lines?

Take a look at this thread.

http://arduino.cc/forum/index.php/topic,68477.45.html

Using pin4 or pin7 to control an lcd (data bus and control lines) causes the UNO to lockup.

Move your LCD connections to anything but pin4 and pin7

I'm going to start a thread in the diplay area about this.

You should have maybe posted this over in the display area - maybe the mods will move it.