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31  Using Arduino / Displays / Re: 2004 LCD partially doesn't work on: July 19, 2014, 09:16:50 am
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It is possible, during i2c scanning, ...

Where did the original poster mention anything about I2C?

Don
32  Using Arduino / Displays / Re: Displaying date on LCD with DS1307 using button inputs on: July 18, 2014, 04:25:51 pm
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Okay. So what would be the cause of this conflict?
The conflict is that you have chosen to use the same pin for both the push-button and for the LCD.

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Bad = Pins 2,3,4,5,11,12,13
Pins 2,3,4,5,11,and 12 are 'bad' because you are already using them for the LCD.
Pin 13 may be bad because the on-board LED is connected to that pin.


Don
33  Using Arduino / Displays / Re: Lcd missing pixels on: July 18, 2014, 04:20:38 pm
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im gonna buy a new one. it was cheap anyway ... I still can't understand how it happened !!
Try to find one that is inexpensive but not cheap.

Don
34  Using Arduino / Displays / Re: LCD black boxes problem! on: July 18, 2014, 04:16:46 pm
Here is my generic step by step approach that should work:

(1) If the module has a backlight then get it working properly.  This involves only pins 15 and 16 on most LCD modules.  Make sure to use a current limiting resistor if there is none on the LCD module.

(2) Get the power and contrast working properly.  This involves only pins 1, 2, and 3 on most LCD modules.  You should be able to just barely see blocks on one row of a two row display and on two rows of a four row display. 

NOTE:  The Arduino has not been used yet, except as a possible source for the power needed for the first two steps.  Do not try to go any further until this is working.  If you don't see the blocks then no amount of program code will help.

(3) Connect the LCD R/W pin (pin 5) to GND.

(4) Connect the six control and data wires between your LCD module and your Arduino.

(5) Upload your sketch and it should work.


Troubleshooting:

If you have a 16x1 display and there are blocks only on the left half of the row in step 2 then use lcd.begin(8, 2); in your sketch.

If you still don't get a display then make sure that your wiring matches the numbers in the descriptor (or vice versa).


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

If you get a display but it is garbled or has some other problems then try again with a 'static' sketch, one that displays a simple message on the top row of the display and then stops.  All of your code should be in setup() and loop() should be empty between the brackets.

Code:
#include <LiquidCrystal.h>

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

void setup()
  {
  lcd.begin(16, 2);                          // put your LCD parameters here
  lcd.print("hello, world!");
  lcd.setCursor(0,1);
  lcd.print("it works!");
  }

void loop()
  {
  }

If you are still having problems then we need to see a photograph of your setup that clearly and unambiguously shows all of the connections between your Arduino and your LCD module.  We also need a copy/paste version of the code that you are actually using, not a link to the code that you think you are using.

Don


35  Using Arduino / Displays / Re: Displaying date on LCD with DS1307 using button inputs on: July 18, 2014, 10:59:38 am
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Any insight or explanation as why this happened would be great.
Because there is a conflict in the use of pin 11. 

Don
36  Using Arduino / Displays / Re: How to underline (indicate) a character on HD44780 LCD without delay() use? on: July 18, 2014, 10:54:38 am
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I didn't use any libraries for interface handling. LCD is controlled with LiquidCrystal.h.
That's not the way I interpreted your original post.

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Can you be more specific with your advice?
Not really.  I was under the impression that you were controlling your LCD using code that you had written that did not involve using the delay() routine and was confused about why you would then consider using cursor() and noCursor().

Don
37  Using Arduino / Displays / Re: How to underline (indicate) a character on HD44780 LCD without delay() use? on: July 17, 2014, 12:28:52 pm
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I didn't use any libraries because the interface is quite simple and decided to code everything on my own.

Since you have already coded everything else without using a library why do you think you have to use the cursor() and noCursor() functions?

The underline and blink are both handled by the 'Display on/off control' instruction.  All you have to do is issue your own version of this instruction and then deal with the required delay using whatever method you used in your other routines.


Don
38  Using Arduino / Displays / Re: Newline char causes odd character on SainSmart 2004 20x4 I2C LCD on: July 17, 2014, 09:23:09 am
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So i will keep that "fancy" chinese char, not a problem, only esthetic.

You might be able to get rid of it by creating a 'blank' custom characters at the appropriate address.

Don
39  Using Arduino / Displays / Re: LCD current draw on: July 17, 2014, 09:02:20 am
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A thousand apologies, my bad for reading too quickly

I do that frequently as well.

Getting back to your original post:

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It says "LED" but it also says "EL", so I suspect the backlight is really electroluminescent.

If you look at the diagrams at the top of the page it appears that there are several different versions, LED backlight, EL backlight, and no backlight..

Don
40  Using Arduino / Displays / Re: LCD current draw on: July 17, 2014, 08:47:43 am
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Most of these units draw about 20 mA or so, I just went and measured it - about 151 mV across the "101" - 100 ohm resistor R8 on the one next to me which would be 150 mA but the USB supply is loaded down to 4.55V by all the junk I have connected.  Which means you can probably  control it directly from an Arduino pin.

This agrees with my experience as well.

When you do the math with the numbers that I (and Jack) supplied you will find out that the required resistance to give the nomnal current is in the order of 7 ohms.   Since most of us use a much larger resistor, typically at least 100 ohms (as on the board investigated by Paul) the actual LED current is much lower than that mentioned in the datasheet and the backlight is still quite bright.  You should have no trouble powering it directly from the Arduino.


Don

41  Using Arduino / Displays / Re: LCD current draw on: July 17, 2014, 08:40:04 am
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Edit: Here is an alternate datasheet, it says backlight requires 120mA typ, 160mA max.

Why didn't I mention those values?  Oh - I did.

Don
42  Using Arduino / Displays / Re: 20x4 LCD problem on: July 17, 2014, 08:37:56 am
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What happens when you print after the display physical memory is random.

It is not at all random.  Did you look at the link in reply #11?

Don
43  Using Arduino / Displays / Re: Help Needed in lcd JHD 162A interfacing with arduino2560 on: July 17, 2014, 08:34:13 am
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Thanx! for reply bro i fix it and it working Well now

Well that certainly clears things up.  It will be a great help for those who look at this thread in the future.

Don
44  Using Arduino / Displays / Re: LCD current draw on: July 16, 2014, 07:13:43 pm
I have a 'non-extended' (one page) version of the data sheet which gives more information about the backlight.  It indicates that the typical operating current is 120 mA and the maximum is 160 mA.

Note that it is your responsibility to assure that there is enough resistance in series with the LED to limit the current to these values.  There may be a resistor on your pc board or you may have to add one externally.


Don
45  Using Arduino / Displays / Re: 20x4 LCD problem on: July 16, 2014, 06:52:34 pm
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But that is the issue. I expect it to be placed on the next line, not two lines down.

Your expectations are too high considering that the controller was designed about thirty years ago.

Have you looked at the link in reply #11?


Don
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