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Author Topic: LCD lighting up, but not displaying text  (Read 1662 times)
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OK so i recently purchased a 20x4 LCD made by Hacktronics http://www.hacktronics.com and i set it up with the following tutorial http://www.hacktronics.com/Tutorials/arduino-character-lcd-tutorial.html I then ran the code on the page and changed the 16,2 to 20,4 and uncommented the lines yet this is not working. The LCD lights up blue but no text is displayed. Im using 330 ohm resistors (im not sure exactly, but there blue with pink and black stripes) but nothing seems to help it. Thank you to anyone who might be able to help!!

EDIT: In the picture my resistor is not shown because i was trying other things to see if it would work, heres a close up on the resistor


* Photo on 4-13-12 at 6.28 PM #2.jpg (196.14 KB, 1080x720 - viewed 42 times.)

* Photo on 4-13-12 at 6.35 PM.jpg (112.1 KB, 1080x720 - viewed 30 times.)
« Last Edit: April 13, 2012, 05:36:13 pm by TheWave » Logged

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We need a clear (focused) picture that unambiguously shows both ends of each wire that connects between your Arduino and your LCD module.  It would help if the picture were oriented properly instead of being reversed.  (Use two mirrors if you have to.)

Where is your potentiometer?

What size is the resistor and where are you using it?


Don
« Last Edit: April 13, 2012, 07:37:16 pm by floresta » Logged

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I guess you didn't solder the male pins to the display. Did I win a price? smiley-wink
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We need a clear (focused) picture that unambiguously shows both ends of each wire that connects between your Arduino and your LCD module.  It would help if the picture were oriented properly instead of being reversed.  (Use two mirrors if you have to.)

Where is your potentiometer?

What size is the resistor and where are you using it?


Don

Ok so Im really new to this stuff, does anyone know of a tutorial or something to help me? I don't know how to get my petentiometer to do anything and I copied the picture on the website exactly and now the LCD won't even light up, I don't know what "size" the resistor is either. I'm sorry
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Ok so Im really new to this stuff, does anyone know of a tutorial or something to help me? I don't know how to get my petentiometer to do anything and I copied the picture on the website exactly and now the LCD won't even light up, I don't know what "size" the resistor is either. I'm sorry

Try the Tutorial at http://www.ladyada.net/learn/lcd/charlcd.html. Be careful with the backlight connections, the text tells all about the resistor but it does not show up in the photographs.  It goes in place of the red wire at pin 15 or the black wire at pin 16.

Don
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Ok so Im really new to this stuff, does anyone know of a tutorial or something to help me? I don't know how to get my petentiometer to do anything and I copied the picture on the website exactly and now the LCD won't even light up, I don't know what "size" the resistor is either. I'm sorry

Try the Tutorial at http://www.ladyada.net/learn/lcd/charlcd.html. Be careful with the backlight connections, the text tells all about the resistor but it does not show up in the photographs.  It goes in place of the red wire at pin 15 or the black wire at pin 16.

Don

Thank you! This looks promising, yet I have a mini breadboard while this seems to be a very large one, in the case of the pretentiometer I don't see how I could replicate this on mine. Any ideas?
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I guess you didn't solder the male pins to the display. Did I win a price? smiley-wink

On a second look maybe you did solder the pins. The picture was not good enough to convince me but since you didn't say anything, I take it as yes you soldered the pins.

Your breadboard is very small, but you have not used the other half of the board. There's plenty of space to set up a potentiometer.
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I guess you didn't solder the male pins to the display. Did I win a price? smiley-wink

On a second look maybe you did solder the pins. The picture was not good enough to convince me but since you didn't say anything, I take it as yes you soldered the pins.

Your breadboard is very small, but you have not used the other half of the board. There's plenty of space to set up a potentiometer.

Ok well I'm sure this is a really stupid question but my petentiometer has 3 prongs that can be plugged into the breadboard. Any help on how to get this to work
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Ok well I'm sure this is a really stupid question but my petentiometer has 3 prongs that can be plugged into the breadboard. Any help on how to get this to work
One end goes to +5V (LCD pin 2), the other end goes to Ground (LCD pin 1), and the center terminal goes to LCD pin 3.  Your potentiometer may physically look different but the connections are the same as those in the tutorial photographs.

Don
« Last Edit: April 14, 2012, 09:37:55 am by floresta » Logged

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One end goes to +5V (LCD pin 2), the other end goes to Ground (LCD pin 1), and the center terminal goes to LCD pin 3.  Your potentiometer may physically look different but the connections are the same as those in the tutorial photographs.

Don
[/quote]


Alright so i did this and followed a tutorial but its still just lighting up as a blue screen. I think the problem is that the contrast is not working. ARRRGGHHHH! I'm frustrated, thank you for your help. Is there any pictures i could post that would be helpful?
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Is there any pictures i could post that would be helpful?
Yes.  See Reply #1.

Don
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Is there any pictures i could post that would be helpful?
Yes.  See Reply #1.

Don


Ok so on my first post i said i followed the tutorial (second url) and on there there is a picture of what the board should look like when finished which i tried to copy exactly but one thing confuses me, whats going on between the 3rd and 1st connections with the resistor. Thank you
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Is there any pictures i could post that would be helpful?
Yes.  See Reply #1.

Don


Ok so on my first post i said i followed the tutorial (second url) and on there there is a picture of what the board should look like when finished which i tried to copy exactly but one thing confuses me, whats going on between the 3rd and 1st connections with the resistor. Thank you

I suggested that you look at Reply #1 for recommendations.  You have posted a copy of your OP (original post).  Each reply to the OP has a reply number - it looks like this « Reply #1 on: April 13, 2012, 07:35:12 PM »


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whats going on between the 3rd and 1st connections with the resistor.
It's the incorrect way to apply the power to the actual display itself.  You should use a 10 K ohm (plus or minus a few hundred percent) potentiometer with the ends connected to +5 V and GND and the center connected to pin 3.  This is commonly called the 'contrast' control.

Don
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Ok so I hooked up the petentiometer to 5v and GBD and the third pin bus however I turn the contrast nothing happens. Should pin 3 be connected to anything other than the wiper
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How about a photo, perhaps the one I asked for two days ago? 

Don
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