1602a 16X2 LCD is blank

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

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.

Chaul:
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.

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.

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

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

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)

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: LiquidCrystal - Arduino Reference
Use the LiquidCrystal() link to get here: LiquidCrystal - Arduino Reference
And there it is under 'Syntax'

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

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

Don

It looks like Vss is not connected in the picture. There doesn't appear to be a jumper in the hole above the pin on the display board. Even before doing any initialization, the OP should be seeing rows of black squares if the power is ok and the the contrast is good.

It looks like Vss is not connected in the picture. There doesn't appear to be a jumper in the hole above the pin on the display board.

That's due to what I mentioned about parallax and the reason for the recommendation to use a long lens.

Even before doing any initialization, the OP should be seeing rows of black squares if the power is ok and the the contrast is good.

I wish I had thought of that.

Don

floresta:

It looks like Vss is not connected in the picture. There doesn't appear to be a jumper in the hole above the pin on the display board.

That's due to what I mentioned about parallax and the reason for the recommendation to use a long lens.

Even before doing any initialization, the OP should be seeing rows of black squares if the power is ok and the the contrast is good.

I wish I had thought of that.

Don

Ok, you caught me. I didn't read it all carefully, I see now where you mentioned the boxes and contrast.

I just read all of this thread and I am having the same problem. I can get the squares and adjust them to very light. However, I do not get any signals (words).

See attached picture.

LCD Setup 1.JPG

I just read all of this thread and I am having the same problem.

That looks like a unique display. Can you give us more information about it?

We can't really verify that your connections are correct without being able to unambiguously follow each wire from one end to the other.

Don

As far as I know it is a standard display. I have attached a photo of the back as well as a better picture of the overall setup and a close up of the LCD wiring.

Setup 1.JPG

Closeup 1.JPG

It looks like you may have now have pin 5 of the LCD (R/W) connected to +5 instead of GND. It appeared to be correctly connected in your original photograph.

Don

You are absolutely right. I must have switched it when I cleaned it up for the last photos.

OK, I put 5 to GND, but nothing changed. If I look really hard at the display I can almost see some movement where the letters should be. This may just be my imagination as I cannot bring it out with any changes in contrast.

I know the last thing to suspect is always the hardware, but I am beginning to think that the LCD might have a problem.

Dan

My face is red! I thought of one more thing so I checked my software and discovered I had it set up for Arduino Uno and not Arduino Mega. I had switched to another project and forgot to change back.

LCD is now working.

A real NOVICE error but then again that's exactly what I am.

Thanks for the help.

Dan

I am also having same Problem , any one solve issue for above

I am also having same Problem , any one solve issue for above

I thought he did solve his problem as reply #23 states "LCD is now working".

Start a new thread for your problem since this one is almost a year old and is solved. Be sure to indicate exactly which display you are using, include your program code, and provide a photograph of your setup if possible and you will get all kinds of help.

Don

Hello, you are powering the circuit only with 3.3 Volts, try in 5 volts and it works fine.
Other problem was your solderings, try to appear bright and smooth like D5 pin in the LCD, do not permit the holes, you just need to use a small quantity of soldering paste at the tip of the iron. And try to mantain the iron tip clean.
And by the way the code was pretty good. Simple and efective...