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Author Topic: Problem with allignment of LCD  (Read 1868 times)
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The Netherlands
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Hello there!

Got my arduino this weekend and started playing around with it and I enjoy it alot. Programming is not too hard as I am studying IT. I got a lcd aswell, it was not to hard to get setup (had to solder pins too it though).

But now I got this:
On the upper row of it starts too high placing the text (1 pixel), this is not a big deal as all text will fit onto it. But on the second row it pushes the pixels up one and pieces of the text fade/fall away. Most of the time with CAPS but some times with normal letters. It also looks like it doesn't use all the pixels it can use (could be wrong here).

To show what the problem is, here are some pictures:
https://www.dropbox.com/s/ag5do0mkytlkyqa/lcdPixels1.jpg
https://www.dropbox.com/s/1yipl0rratirmmt/lcdPixels2.jpg
https://www.dropbox.com/s/6il3z79j5vv1y4p/lcdPixels3.jpg

Hope you can help me out!

Thanks in advance,

Guy
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Western New York, USA
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Hope you can help me out!
You will have to help us out a bit first.

We have to know what type of LCD you are dealing with.

We have to know what program code you are using.

We have to know how your LCD is interfaced with your Arduino.


Don
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It is defective: the 2nd line should have shown its top row, as the 1st line did.
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It is defective: the 2nd line should have shown its top row, as the 1st line did.

There are 2 lines missing then, on the bottom row. Could this be a bad connection on the pins? I soldered them myself so it could be.
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Was it supposed to do that?
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See reply number one (post number two!). If anyone can sort it out for you Don can.
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Hope you can help me out!
You will have to help us out a bit first.

We have to know what type of LCD you are dealing with.

We have to know what program code you are using.

We have to know how your LCD is interfaced with your Arduino.


Don

It's a 1602a LCD, it doesn't say more on the lcd.

Here is my code:
Code:
/*
lcdSetup - Guy
Basic setup for a LiquidCrystal display


Connections:

RS = 12
RW = 11
E  = 10
D4 = 6
D5 = 7
D6 = 8
D7 = 9

A = 5V   (+)
K = GND  (-)

VDD = 5V  (+)
VSS = GND (-)
V0 = PotMeter Middle Pin

PotMeter:
Right Pin = 5V  (+)
Left Pin  = GND (-)

*/
#include <LiquidCrystal.h> //Include the LiquidCrystal library

LiquidCrystal lcd(12, 11, 10, 6, 7, 8, 9); //Setting a LiquidCrystal as 'lcd'
void setup()
{
  lcd.clear(); //Clear the display
  lcd.begin(16,2); //Define the Length and Rows
}

void loop()
{
  lcd.setCursor(0,0);
  lcd.print("Hello forums!");
  lcd.setCursor(0,1);
  lcd.print("Pixels MESS up");
  delay(100000);
}

Here is a pic of the setup:
https://www.dropbox.com/s/77mj452jl205gev/lcdPixels4.jpg
Note: This is a slightly different pin allignment then I now use. But it did the same thing.

I also tried using all data pins, didn't change anything.
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There are 2 lines missing then, on the bottom row.

The bottom row is for the underline / cursor. The font itself is 5x7. Check the datasheet.
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I also tried using all data pins, didn't change anything.

It has nothing to do with external connections.

The lcd is toast.
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I also tried using all data pins, didn't change anything.

It has nothing to do with external connections.

The lcd is toast.


Damn that, ordering a new one then. Any good places to get one?
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It's a 1602a LCD, it doesn't say more on the lcd.
That's enough to get started.

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Damn that, ordering a new one then. Any good places to get one?
I wouldn't give up yet.

A character mode LCD like the one you have does not have to be refreshed.  Therefore the code that you have in loop() should be in setup() and loop() should be blank.

But lets go back a step.  What happens when you connect just the backlight, the power, and the contrast (pins 15, 16, 1, 2, and 3)?

Back one more step - are you using a resistor in series with either backlight lead?


Don
« Last Edit: December 11, 2012, 11:20:38 am by floresta » Logged

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Your LCD is good, dont scrap.
Just measured the output voltages of the Arduino input to the LCD. and tell what voltage at what pin you are getting wrt gnd. I think one of your arduino pin out has low voltage (any led, resistor you added)
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But lets go back a step.  What happens when you connect just the backlight, the power, and the contrast (pins 15, 16, 1, 2, and 3)?
Did this, when I put the contrast all the way up only the top row changes contrast. The bottom one doesn't.


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Back one more step - are you using a resistor in series with either backlight lead?

I am not using a resister in series with either of the backlight lead, is this needed?
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Any good places to get one?

Tough to know in your backyard but I got mine (48 of them, in one box) years ago from digikey.
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But lets go back a step.  What happens when you connect just the backlight, the power, and the contrast (pins 15, 16, 1, 2, and 3)?
Did this, when I put the contrast all the way up only the top row changes contrast. The bottom one doesn't.
That is exactly what is supposed to happen.  Most likely your LCD is not defective but personally I wouldn't absolutely declare it good or bad based on what I know so far.

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Back one more step - are you using a resistor in series with either backlight lead?

I am not using a resister in series with either of the backlight lead, is this needed?
These backlight LEDs always require some sort of current limiting.  Sometimes there is a resistor on the pc board, but most of the time you need an external one.  I would start with 150 ohms and see what happens. 

Without this resistor you could damage the LEDs but it is more likely that your power supply is not capable of supplying enough current to do so.  In this case it's output voltage could be dropping and this could possibly be causing the LCD to malfunction.


Don

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Without this resistor you could damage the LEDs but it is more likely that your power supply is not capable of supplying enough current to do so.  In this case it's output voltage could be dropping and this could possibly be causing the LCD to malfunction.[/color]

I put a 1k resister on the backlight and this fixed only the first character. Don't know what it could be really.
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