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[on:]

Hello there^^

I`ve 2 Arduinos, one Uno R2 SMD and one Uno R3 SMD, 2x 16x2 HD44870 LCD screens nad a lot of wire. The setup with the LCD worked great, but yesterday I`ve got only a black line on the display, like it isn`t initialized. So I tested it with my own code, then with the example Hello world code, and alway the same. Then I tested it with the second board and display and the same error, the configuration that worked very well the last few weeks isn`t working now. I`ve testetd the wire, too, all cables are okay, I am using a Cat 5 patchcable - should be ok, I guess.
So I played a little with the contrast, but I thought, that it wouldn`t help, so I was right. I tried a 10K potentiometer and a 26K, then I tried a 6,8K ohm resistor for negative and 2 470 ohm resistors for positive, but the same problem. SO I think it is nothing wrong with the contrast ...

Just yet I`ve connected it to 8, 9, 13, 12, 11, 10, just to be sure, that it`s not a problem with the controller, and I`ve testet all digital outputs with a led and the blink scetch and all outputs are ok. I`ve checked the 5V output, too, and there is no problem with a constant voltage ...

I am using the example scetch at the moment:

Code:

#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 13, 12, 11, 10);

void setup() {
  lcd.begin(16, 2);
  lcd.print("hello, world!");
}

void loop() {
  lcd.setCursor(0, 1);
  lcd.print(millis()/1000);
}

Anyway, it worked all very well, until yesterday, now I am getting this strange black line in the first row, like it isn`t initialized, as I wrote.  It doesn`t matter how the lcd is connected, always the same. Contrast doesn`t matter, too. And which board, cables, lcd and outputs I am using, doesn`t matter, too.

Whats the problem there?! I can`t find it ... anyway.

mfg Dome94

[Reply #1 on:]

As you have noted, the single black row of blocks indicates that the LCD controller is not correctly initialized.  

Since you know that the code is good this leaves an improper or bad connection.  

Since neither display works this would tend to rule out poor soldering at the display end.

Things tend to be pointing to your patch cable.  If you are using a solderless breadboard you could have a problem there as well.

I`ve testetd the wire, too, all cables are okay

How did you do this?  You really have to test each wire from end to end.  This means from the LCD PC board to the Arduino PC board including all intermediate contacts.  You also have to check for shorts between adjacent wires.

Don

[Reply #2 on:]

Hi,

the soldering at the lcd is/was ok, I`ve used it 2 weeks as I said and I didn`t resolder it. Well, I`ve tested the patchcable only with a multimeter, while testing the patchcable wasn't connected.
My soldering wire is: Stannol with copper 1,5mm (S-Sn60Pb38Cu1) RF32

I`ll test it on the breadboard later.
If it will not work, I`ll buy some lcds on ebay, again. One lcd costs only 3€, so this isn't too much.