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Author Topic: 1602a 16X2 LCD is blank  (Read 6899 times)
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I am using 1602a 16x2 LCD with Arduino Uno V3. My board version is 1.0.3

I am using following code:

Code:
/*
  LiquidCrystal Library - Hello World
 
 Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
 library works with all LCD displays that are compatible with the
 Hitachi HD44780 driver. There are many of them out there, and you
 can usually tell them by the 16-pin interface.
 
 This sketch prints "Hello World!" to the LCD
 and shows the time.
 
  The circuit:
 * LCD RS pin to digital pin 12
 * LCD Enable pin to digital pin 11
 * LCD D4 pin to digital pin 5
 * LCD D5 pin to digital pin 4
 * LCD D6 pin to digital pin 3
 * LCD D7 pin to digital pin 2
 * LCD R/W pin to ground
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)
 
 Library originally added 18 Apr 2008
 by David A. Mellis
 library modified 5 Jul 2009
 by Limor Fried (http://www.ladyada.net)
 example added 9 Jul 2009
 by Tom Igoe
 modified 22 Nov 2010
 by Tom Igoe
 
 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/LiquidCrystal
 */

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
//LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
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!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);
  delay(200);
}


Here is the datasheet:



I attached everything as suggested and also soldered the lcd.

But the LCD is totally blank. The back light is working fine. I added the delay(200) after reading some threads with similar issue but same problem.

Any help please?



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One more thing, when I compile the code/upload it, it shows no error and arduino led suggests the the code is uploaded successfully.
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Hello

I am just dealing with the same problems, except mine show some squares on the screen. I do not have much knowlegde in this as this is my first time working with it, but have you installed the 10K potentiometer? when i turn my down the contrast is turned down and then the display look like yours.
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Your photographs are better than some that I have seen but it is still difficult to follow all the wires.  It looks like your connections are OK, but I can't be sure.

On the other hand your soldering looks like it could use some improvement.  I suggest you try and get all of the LCD connections to look like the one at D5, nice and shiny with no holes.  You already have used too much solder on each joint so don't add any more unless you need more flux, then be sure to remove all of the excess solder.

Here's my quick and dirty LCD setup procedure from a recent post:

1.  Get the backlight working first (pins 15 and 16).
2.  Connect the power and the contrast next (pins 1, 2, and 3).  Any potentiometer between 5K and 50K will work.  With the potentiometer at one end of it's range the display will be blank and at the other end you should see boxes on the top line of the display.  Adjust the potentiometer until the row of boxes is visible, but dim.  The voltage at pin 3 should be around 0.5v at this point.  If you do not get this behavior then it makes no sense to continue since no amount of programming will fix things.
3.  Connect the other seven pins (4, 5, 6, 11, 12, 13, and 14) and load up your sketch.


Quote
One more thing, when I compile the code/upload it, it shows no error and arduino led suggests the the code is uploaded successfully.
See the last sentence of #2 above.

Don
« Last Edit: January 31, 2013, 03:49:49 pm by floresta » Logged

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Yes, the connection to RS in particular (4th from the left) looks like it hasn't taken. The solder should flow into a nice blob. If it isn't soldered properly, pushing the LCD into the board may push the pin up and not touch the contact.
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Your solder connections do look bad but I am pretty sure (95%) you have another problem.  The power busses at the top left corner of the picture ( red, orange, yellow and white wires ) are not connected to where you bring in the power at the top right of the picture (blue and white wires).  The power busses on your proto boards are split in half as indicated by the broken red and blue lines.

The solution is to jumper +5 and ground from the left side to the right side.  That should fix one problem.
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Your solder connections do look bad but I am pretty sure (95%) you have another problem.  The power busses at the top left corner of the picture ( red, orange, yellow and white wires ) are not connected to where you bring in the power at the top right of the picture (blue and white wires).  The power busses on your proto boards are split in half as indicated by the broken red and blue lines.

The solution is to jumper +5 and ground from the left side to the right side.  That should fix one problem.

That certainly looks like the problem or at least one of the problems that he has.  I'd like to think that I would have picked up on that if I had seen the entire upper photograph.  I just figured that the upper photo didn't show the entire board since there was no scroll bar below it and that's one of the reasons that I complained about not being able to follow all of the wires (the other is parallax, but you can't do much about that with a cell phone camera).  I didn't look for a scroll bar below the lower picture since it didn't need one.  I guess the strange implementation of a single scroll bar for two separate photographs is due to some interaction between the forum software and the browser.

Don
« Last Edit: February 01, 2013, 08:02:26 pm by floresta » Logged

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Don:

The scroll bar got me too.  I did not see it until I scrolled down to look at your answer, then I saw it.

I think he should be on his way if he reflows the solder joints and jumpers the power buses.

Joe
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I have the same problem, but I've connected an I2C backpack to this 2x16 character LCD. I'm running some HelloWorld_i2c example, but no text is displayed even though the example is blinking the backlight as it should.
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I have the same problem, but I've connected an I2C backpack to this 2x16 character LCD. I'm running some HelloWorld_i2c example, but no text is displayed even though the example is blinking the backlight as it should.
Please start another topic to keep it separate from this one.
Post quality pictures of your setup and post your code.
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The power busses at the top left corner of the picture ( red, orange, yellow and white wires ) are not connected to where you bring in the power at the top right of the picture (blue and white wires).

due to optical illusion. You can count the pins, from right to left, as the leds for sure  work so pin 15/16 are right.
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due to optical illusion. You can count the pins, from right to left, as the leds for sure  work so pin 15/16 are right.

That is what I thought at first, except I thought there was a problem with the data lines going to the lower numbered Arduino pins.  We may have to specify photos shot from directly above with a long lens.

I didn't think there was a power problem since the backlight was working, until JoeO mentioned the power bus.  I looked at my breadboards, which don't have that gap in the pin connections, and they don't have the gap in the blue and red lines either.

Of course this problem would pop right up in step two of my three step procedure (or with a quick voltmeter check on the power pins).


Don
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Here is a link to one of my previous posts regarding bread boards and their power buses.  They are not what you may think.

http://arduino.cc/forum/index.php/topic,141319.msg1061791.html#msg1061791
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Hi all, this is my first post,my name is Francisco Javier; I am  from Menorca, spain, so sorry if my english sounds bad.
I am really new to arduino, but I got to run a LCD like this one.
Maybe I am telling a foolishness, but I have seen in the code you are using the pins 11 and 12 as data and not for Enable and RS. I am wrong or is it??
(12,11,5,4,3,2,1) instead of (5,4,3,2,1,12,11)

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Quote
Maybe I am telling a foolishness, but I have seen in the code you are using the pins 11 and 12 as data and not for Enable and RS. I am wrong or is it??
(12,11,5,4,3,2,1) instead of (5,4,3,2,1,12,11)
You can use any available Arduino I/O pin to feed any of the LCD pins.  The values that you use in the LiquidCrystal.lcd() statement have to match your particular circuit connections.

They have very cleverly made it difficult to find the explanation for this. Here is how:
Start here: http://arduino.cc/en/Tutorial/LiquidCrystal
Scroll down to the bottom
Use the Liquid Crystal Library link to get here: http://arduino.cc/en/Reference/LiquidCrystal
Use the LiquidCrystal() link to get here: http://arduino.cc/en/Reference/LiquidCrystalConstructor
And there it is under 'Syntax'

Of course a simple comment would go a long way as well:

Code:
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);      // put your pin numbers here

Don



« Last Edit: February 02, 2013, 02:15:13 pm by floresta » Logged

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