1602a 16X2 LCD is blank

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...

I had a similar issue at first with just getting a backlight, not realizing that the pot was actually the contrast control. Sometimes it's the simplest things that cause the most complex seeming errors.

Hello I was having the same problem with the same LCD board i bought off ebay. I thought the pinout was reversed, but it was not. Wire it up just like in the picture in the start of this post. Also i added +5v and GND to pins 15/16, the ones labeled LED+ and LED-.

also, since i did not have a 10k pot handy, i substituted for a 1 or 2k resistor (RRRG)and took it to ground. The other end of the resistor i put on the 3rd pin Vo, and my screen instantly gave me the right contrast with the row of solid boxes on the top line.

From there it was just a matter of getting my pins contacted on my breadboard with more solid connections.

if i had a loose wire, i would get all kinds of garbage and refreshes on the screen. Once i locked down the connections more solidly, everything worked right by hitting the arduino reset button.

same problem
note: yellow = data
orange = Anode
Blue = ground
white = ground (couldn't get another blue)
pic:

You have re-resurrected an old thread.

Start a new thread and I will tell you exactly what is wrong.

Don

I can tell you right now - so many people come here with the same problem.

You have not connected your display to the Arduino. You have a pin header plugged into the breadboard, but you only have your display sitting on the pin header - you need to actually connect it by soldering.

I can tell you right now ...

I could have told him as well, but I didn't - for a good reason.

Now this thread is doomed to be resurrected again ... and again ... and again ....

Don

I had notified the moderator late last night before there were any replys hoping that it would be placed into a new thread. No such luck.

floresta:
Now this thread is doomed to be resurrected again ... and again ... and again ....

What's with this fetishism about "old threads"?

Old threads are supposed to be about solved problems. They are supposed to be the things that people with a problem will find by searching in order to answer their problem without having to post a new thread and wait on the benevolence of the helpers. Is that not the purpose of archiving thousands of them, instead of simply deleting them after the nominal "expiry" period of 120 days or whatever?

An old thread containing multiple - correct - solutions to a particular variety of problems is a valuable resource. That's exactly why you have "stickys" in the index page. You should want this to happen instead of having the same situation confused over hundreds of threads, all asking the same question.

I agree with your analysis but I do not think that this particular thread is a good example of one that should be perpetuated.

Don