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Topic: lcd screen showing blocks even though wiring is correct (Read 506 times) previous topic - next topic

chincheng

I used the same code and board to test 20X4 LCD module and it works good!!

floresta

None of those photos allow us to unambiguously follow each wire from the LCD back to the Arduino.  We have to be able to do that in order to verify your wiring.

You should also check the continuity of each of those jumper wires, especially if they are inexpensive imports.

Don

bperrybap

Malti,
You need to show the EXACT wiring you are actually using.
And do not change it or modify it after you show the wiring you are using.

The wiring in photo 20170409_120347.jpg does not appear to match the others.
For sure the wiring in 20170409_120347.jpg does not match the wiring in 20170412_082933.jpg
The colors of the wires being used are different and while the backlight and some pixels appear to be on in photo x347.jpg there are no visible connections to either the backlight anode or cathode.
Therefore these photos of are completely different wiring.

Details matter.
In cases like this where the LCD is not working, it is a wiring issue.
In order to get help, you must show how the LCD is ACTUALLY wired up and show it in a way that allows other to visually inspect all the wiring to look for issues.

--- bill

bperrybap

Now i am facing another problem after few days as it happened two weeks before that my arduino is not able to connect with my pc .what is surprising is that sometimes it connects while sometimes not.
Different problem, start a different thread.
--- bill

Malti

I am sorry for that .
But i didn't  actually remember that i took these photos on different occasions since i changed the wiring every time.what i mean by this is that the code remained the same as well as the connections but the only thing that changed was the color of the wires aince every time I  faced this problem i thought that there is some mistake in the way i am connecting.
And in some photos where the blocks are being showned is where the lcd screen is showing aomething else it shows nothing.

floresta

Did you check each of the wires for continuity?

We are still waiting for a suitable photograph, without that we are only guessing.

Don

Malti

Here's  a video of that.
Warning: dont keep the volume full.sorry for background  noise , construction work goin on



https://drive.google.com/file/d/0B-uozw6XsukkT0xCaTNNMXZONUU/view?usp=drivesdk

floresta

A video is generally not a good way to check out wiring and since I use a satellite internet connection I am reluctant to waste my limited monthly data trying.  Surely you can take a simple photo that shows your entire setup. 

In any case the pictures are useless without the accompanying code.  It's been nearly a week since I requested both.

Don

tcurnewmb

just had these issues with an old one, timing (letting pins settle) and making sure the init happens properly has a lot to do with it, for example:

http://forum.arduino.cc/index.php?topic=471157.0

the problem i was having is i have to init it as a 16x2, then an 8x2, because even tho the screen is 16x1, it is addressed as 8x2 but if the extra bytes at 8-15,0 and 8-15,1 aren't initialized, it doesnt work. who tf knows.

HTH

floresta

Quote
... but if the extra bytes at 8-15,0 and 8-15,1 aren't initialized, it doesnt work. who tf knows.
I do - and this is rubbish.  

A 16x1 with only one chip (or epoxy blob) on the back must be initialized as an 8x2.  Then position the cursor at (0,0) to write the first 8 characters and re-position the cursor to (0,1) to write the next 8 characters.  That's all there is to it.

Don

Malti

sorry guys for not replying
but as i have already mentioned that i am new to arduino but i have done so many tutorials and this was my first tutorial with lcd screen so i am again sorry that i cant understand what are you trying to say so if you tell that me in code like what i need to change in my code so that i may understand it better.
thanks.

floresta

Quote
... so i am again sorry that i cant understand what are you trying to say ...
Here it is again - I don't know how to make this any clearer:

In order to address your problem we must see a photograph that allows us to easily follow each wire from the LCD to the Arduino.  We also have to be able to see the power and contrast connections.  

We also have to see the actual code that you are using so that we can verify that the numbers in the constructor (LiquidCrystal lcd...) match your wiring.

Don


Malti

So here is the 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
 * LCD VSS pin to ground
 * LCD VCC pin to 5V
 * 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(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);
}

Malti

https://drive.google.com/file/d/0B-uozw6XsukkTU1OSkJFcHJGdDQ/view?usp=drivesdk

https://drive.google.com/file/d/0B-uozw6XsukkQnlUcldsV3V3QnM/view?usp=drivesdk

https://drive.google.com/file/d/0B-uozw6Xsukkam1tbURwMm5JSU0/view?usp=drivesdk


https://drive.google.com/file/d/0B-uozw6XsukkTTVjTDNTVmtKYWc/view?usp=drivesdk


https://drive.google.com/file/d/0B-uozw6XsukkdXhnQ01BRF9yM3M/view?usp=drivesdk


https://drive.google.com/file/d/0B-uozw6XsukkbW00Z1RJUV9qdW8/view?usp=drivesdk

bperrybap

It has been ten days since we started asking for photos to be able to evaluate your wiring.

I will repeat the message from post #26:
Here it is again - I don't know how to make this any clearer:

In order to address your problem we must see a photograph that allows us to easily follow each wire from the LCD to the Arduino.  We also have to be able to see the power and contrast connections.  
None of the photos allow seeing the connections all the way from end to end.
For example look at photo ...943, the green wire on the pot, where does it go?
There is no way to tell if connects to the positive rail, the ground rail, or pin 16 of the LCD.

In photo ..039, the yellow wire in arduino pin 4, does it connect to arduino pin 13 or off somewhere else?
The brown wire in arduino pin 2, does it connect to the ground rail or off somewhere else?
The orange wire in arduino pin 5, does it connect to the pot, the ground rail, or off somewhere else?
The white/grey wire in arduino pin 3, is it going to the pot or off somewhere else?


You get the idea. All  your photos have this issue.
The photos are simply not good enough to verify the wiring.


From looking at some of the photos. The soldering is pretty bad.
There could be some soldering issues.
D4, D5, & D7 look particularly bad.
In photo ...943, it looks like there might be short between pins 1 and 2.
It may just be a shadow as if those were shorted, I would not expect anything to work as that would be a short of the main power connections.

I'd recommend that you reheat the solder on the pins to get it to flow out.
I'd recommend that you remove the lcd from the bread board before doing this so you don't damage the bread board.

---bill

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