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First of all i'd like to say hi guys!:)

Secondly I connected 1602a liquid crystal to my arduino duemilanove, and it only shows the first row bull black squares, but no text. I've already checked many posts, but none of them solved my problem. Please help. Thanks in advance.

There's a 10k pot in the system

connection:

lcd - arduino

vss - gnd
vdd - vcc
v0 - output of 10k pot
rs - 7
rw - gnd
e - 8
d4 - 9
d5 - 10
d6 - 11
d7 - 12
A - vcc
K - gnd

sketch code:
Code:
#include <LiquidCrystal.h>

LiquidCrystal lcd(7, 8, 9, 10, 11 , 12);

void setup() {
  delay(2000);
  lcd.begin(16, 2);
  lcd.write("a");
  lcd.setCursor(0,1);

}

void loop() {
    delay(100);
    lcd.write("Hello");

  }
« Last Edit: March 04, 2013, 06:35:56 pm by oboforty » Logged

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Quote
I've already checked many posts, but none of them solved my problem.

First of all your sketch is wrong.  Any information that is not going to change should only be sent to the display once.  You should remove all of the steps that you have in loop (leave loop blank between the curly brackets).  If you really want to display "Hello" then do so in setup.

If that doesn't fix things up then you should start over.

Here are the steps that you should follow to get your display working.
(1) Get the backlight working, this typically involves only pins 15 and 16.  Make sure it has a series current limiting resistor if it needs one.

(2) Get the contrast working, this involves pins 1, 2, and 3.  You should get a blank display with the potentiometer at one end, and some really dark boxes on the top line of your display with the potentiometer at the other end.  You should adjust the potentiometer until you can just barely see the row of boxes. 
Do not proceed until this is working as described, if you do then you will just be wasting your time.

(3) Connect the LCD control and data lines to your Arduino.  Do not forget to deal with LCD pin 5 or the display will not work, it is typically connected to GND.

(4) Load your sketch and see if it works.

If your display still does not work you are not going to get any really reliable help until we have more specific information.  We need as much of the following as possible:
(1) A photograph that allows us to unambiguously follow each wire from one end to the other.

(2) A copy of the sketch that you are using.

(3) A link to the datasheet for the display.

(4) A description or photo of the results of running your sketch.


Don
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Assuming all your wiring is correct, try using

lcd.print("hello");

instead of lcd.write. "Print" should be orange.

Then check the standard Hello world example. Your code is not very sensible, but the first priority is peace of mind...
« Last Edit: March 04, 2013, 07:07:08 pm by Nick_Pyner » Logged

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I used the original sketch code, I only put lcd.write into the loop to check if the arduino sends data at all. I already rewired it a several times. All I managed to get was the blank boxes in the first row.

(1) the wires are connected very chaoticly, but trust me I connected them exactly how the official tutorial said(i did it like 10 times):
http://arduino.cc/en/uploads/Tutorial/LCD_bb.png
I also connected pins 15 and 16 with vcc GND since it has backlight. I also read other tutorials for this particular model and it was the same.

https://docs.google.com/file/d/0B8PnX3XJPEKBN2RQZjUyNnJ6c1k/edit?usp=sharing

(2) https://docs.google.com/folder/d/0B8PnX3XJPEKBdjU1bjNCenFWREE/edit?usp=sharing

(3) http://oomlout.com/LCDD/LCDD-DATA-BC1602A.pdf

I get the same result for the helloworld example too.
« Last Edit: March 04, 2013, 07:23:09 pm by oboforty » Logged

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I also connected pins 15 and 16 with vcc GND since it has backlight. I also read other tutorials for this particular model and it was the same.

https://docs.google.com/file/d/0B8PnX3XJPEKBN2RQZjUyNnJ6c1k/edit?usp=sharing
If this is a picture that you took of your setup then the cause of your problem is obvious, the connections to the LCD module require solder.

If this is something that you found on the internet then make sure that you don't follow any other 'help' from this source.


Don

Edit:  Your backlight requires a series current limiting resistor.  So it looks like you have ignored both of the highlighted sections of my first post.
« Last Edit: March 04, 2013, 08:23:39 pm by floresta » Logged

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