1602A does not show text

Hallo
I try to use the 1602A display with my Arduino Uno V3 but it does not work.
See my attachments on how I cabled it.
It should write some text but only the back light and the contrast work. The contrast I set up with some resistors, as I have no potentiometer. I read post #3 of topic 146173.0 so I set it to show the boxes dim. Doesn’t change the result, and I experimented with different contrasts.

My code is from Ein LCD Display per Arduino ansteuern but I tried the code from this forum too: 1602a 16X2 LCD is blank - it seems that there was a similar problem in this post. The code seems to work, no errors on compiling and upload (I use the create.arduino.cc web editor on a macbook with OS 10.11).
I checked the cables twice with my digital Voltmeter and the circuits and cables all seem ok.

I am finished with my Latin now.
Some help is appreciated.
Thank
Frank

We have to be able to follow each wire from your display back to the Arduino and none of your photos are quite good enough for us to do that.

From what I can see it looks as if you may be using Arduino pins 13 and 12 instead of pins 12 and 11 for RS and RW.

Don

Unfortunately not. 11 and 12 is correct set.
I have checked the cables several times also the connection with the multimeter.
maybe the attached photography is better

Damn! Attachmenting is not woeking with my phone :frowning:

EDIT: did it now with the computer. Picture is helpful now?

Picture is helpful now?

Not really.

Are you able to follow the wires that disappear off the top of the picture?

Can you see the connections to the lower numbered Arduino pins?

Why do you have similarly colored wires adjacent to one another in two places? Wouldn't it make sense to swap one of the green wires with one of the yellow ones?

Are you sure that you checked the continuity of all of those jumper wires, they are well known to be troublesome?

Don

francwalter:
EDIT: did it now with the computer. Picture is helpful now?

It is not helpful.
We can not clearly see where the wires are going.
You have wires going into space out of the frame of the photo and then we can't see where they are going especially since so many of the wires are green.
And then the looking down view is very difficult to tell which pins are being used on the Arduino.

You need to post a photo that some one else could use to replicate your wiring.
In order to do that, they need to see where every wire is going.
Even with your 5 photos I still can't tell how you have things wired up.
It also looks like the wiring in IMG_20170621_20576-1 and IMG_20170621_205916-1 not the same as the wiring in IMG_20170622_140130-1 with respect to the RS and EN pins.

--- bill

Sorry for the bad fotos. I could do more but I think the result would not help much more.

So I again checked the wiring with my multimeter tool and still found no interruption or explanation for the not working text.
I have wired (from LCD pin-number to Arduino pin-number/name of pin):

1 (VSS) → GND
2 (VDD) → 5V
3 (V0) → 0.5 V (instead of a potentiometer I used resistances: 5V → 11kOhm → 3 (V0) → 660 Ohm → Gnd)
4 (RS) → 12
5 (RW) → GND
6 (E) → 11
7 (D0)
8 (D1)
9 (D2)
10 (D3)
11 (D4) → 5
12 (D5) → 4
13 (D6) → 3
14 (D7) → 2
15 (A) → 5V
16 (K) → GND

All these cables are going through from start to end, no interruption and no short circuit I found.

I had unfortunately not enough colored cables so I had to use not the right ones, that is the only reason for my repeating colors where I wanted to use the appropriate colors :frowning:

I had done some electronics in my childhood that why I think I could wire it up correctly but surely I made some mistake.
But after all, is it not possible that this LCD is just broken?
I bought it new though, from China.

This is my code:

#include <LiquidCrystal.h> //LCD-Bibliothek laden

LiquidCrystal lcd(12, 11, 5, 4, 3, 2); //In dieser Zeile wird festgelegt, welche Pins des Mikrocontrollerboards für das LCD verwendet wird (Am besten erstmal nicht verändern).

void setup() 
{
lcd.begin(16, 2); //Im Setup wird angegeben, wie viele Zeichen und Zeilen verwendet werden. Hier: 16 Zeichen in 2 Zeilen.

}

void loop() 
{
lcd.setCursor(0, 0); //Startposition der Darstellung auf dem LCD festlegen. lcd.setCursor(0,0) bedeutet: Erstes Zeichen in der ersten Zeile.
lcd.print("www.funduino.de"); //Dort soll der Text „www.funduino.de“ erscheinen. Der Befehl lcd.setCursor ist dem Mikrocontrollerboard durch das Aufrufen der Bibliothek bekannt.
lcd.setCursor(0, 1); // lcd.setCursor(0,1) bedeutet: Erstes Zeichen in der zweiten Zeile.
lcd.print("Viel Erfolg"); //Dort soll dann der Text „Viel Erfolg!!!“ auftauchen.
delay(200);  
}

francwalter:
Sorry for the bad fotos. I could do more but I think the result would not help much more.

It isn't the quality of the photos. The quality, focus and lighting is very good.
The issue with the photos is the angles and composition.
Back up a bit and show everything and then show the headers from the side so that we can see the wires going into them vertically so that there is no parallax issue.
This will allow us to verify that the wires are going the proper places.

--- bill

So that means, if the wires are indeed going in to the right places, there is nothing more I can do to fix?

francwalter:
So that means, if the wires are indeed going in to the right places, there is nothing more I can do to fix?

No. Not necessarily. The wires, or the pins could be bad or not making proper connections.
Or their could be a short in between the wires of the clump of resistors being substituted for a pot.

The soldering looks a bit suspect on a few LCD module pins.
(I can see a fully open hole on a few of the lcd signal pins)
Overall, the photos are simply not good enough for us to be able to tell if there are any wiring or soldering issues.

In a little over 8 years of seeing many people on the Arduino forum with LCD issues , I can count the bad LCDs involved on one hand - and I don't need all five fingers.
So the likelihood of a bad LCD module is quite low.

I've seen cases with poor solder connections, bad wires, bad bread board connections, not making connections between a pin and an arduino header on the Arduino board and bad pots.
I've also seen many cases where the person fully believes that the wiring is correct but it turns out that the wiring was in fact incorrect.

Also, from the little I can see in the photos, it appears that it was wired two different ways.

If we can't see clear photos of the wiring and the soldering we simply can not provide any feedback with respect wiring or soldering issues, and in my experience those are the two areas that are most likely to have issues.

--- bill

OK, thank s, I put some other foto now :slight_smile:

Assuming you are using this constructor: LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
Then the wiring matches and looks ok.
However; some of the soldering doesn't look so good.
In particular the E signal. I'd go add some solder to all the connections that still have an open hole on the LCD.

That said, there may be an issue with your resistors being used instead of a pot.
i.e. I don't see any pixels at all so maybe it is actually working but the contrast adjustment is way off?

If you disconnect E and RS and then ground pin 3 (vo) do you see pixels when you power up the LCD?

--- bill

bperrybap:
Assuming you are using this constructor: LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

Yes, that is my code (see above).

bperrybap:

However; some of the soldering doesn’t look so good.
In particular the E signal. I’d go add some solder to all the connections that still have an open hole on the LCD…

OK, soldered it again and filled the wholes, see images.

bperrybap:
…If you disconnect E and RS and then ground pin 3 (vo) do you see pixels when you power up the LCD?

Yes, see image. When I tried it with the resistors, I tried all Voltage parts between them, I searched I while till I found these resistor values.
EDIT: now I found a 10k pot and used that. Same result with this. No text is visible.

What irritates me is the lower field, it is half size only. The upper row seems normal to me. See picture IMG_20170628_141924.jpg
The upper line is 8 px high the second (bottom) line is only 3 px high. This normal?
Maybe indeedly broken?

Excellent photos. I wish they were all that good.

Your soldering looks fine. Your Chinese jumper wires do not look as if they are intimately connected to the breadboard. Push them in snugly.

Your 11 pixels high means that it thinks it is in 1-line mode.

Double check the wiring. Reload the example sketch. You should be fine.

David.

Did you power cycle the LCD when you did the test in photo IMG_20170628_141924.jpg ?
After disconnecting RS and EN to do the test, it is critical that you power cycle the LCD to ensure that no previous initialization was done to allow the LCD to start up from a clean known state.
Or for that matter when there are issues like this, the LCD should be power cycled between every single test.
i.e. if you change anything, you need to power cycle the Arduino and LCD to test it.

I see a single line of blocks on my 16x2 display when all the wires are connected to the LCD but RS and EN are disconnected when the LCD is power cycled.

We need Don to comment.
Assuming the LCD was power cycled,
shouldn't the LCD be showing a single row of pixels in photo IMG_20170628_141924.jpg instead of the blocks spanning multiple rows?
He disconnected RS and EN which means that the only initialization being done is what the LCD is doing itself.


The IDE bundled LiquidCrystal library puts the display into 1 line mode before begin() is called.
begin(16,2) will change it out of 1 line mode.
Maybe there is an issue in the wiring or LCD timing that is causing the 2nd initialization to not work correctly.

--- bill

We need Don to comment.

I'm still waiting for the photo that allows me to unambiguously follow each of the six wires that connect the LCD to the Arduino.

The extra three rows of pixels could possibly be from an initialization for a single line display with a 5x10 font although that doesn't explain the 11th row of pixels. Such an initialization could possibly result from miswiring.

I suggest that he remove all of the wires between his breadboard and Arduino and start again with the outline that I recently (re)posted here --> http://forum.arduino.cc/index.php?topic=485667.msg3316081#msg3316081

When he replaces the wires between the breadboard and the Arduino in step 4 he should make sure that adjacent wires do not have similar colors.

Don

floresta:
The extra three rows of pixels could possibly be from an initialization for a single line display with a 5x10 font although that doesn't explain the 11th row of pixels. Such an initialization could possibly result from miswiring.

After a power cycle, is what is on the display in photo IMG_20170628_141924.jpg valid on a 16x2 display given RS and EN are not connected to anything?
which means that no host initialization is happening.

--- bill

I don't think that display is valid under the conditions you describe. Of course we don't know the conditions under which the picture was taken.

Don

floresta:
I don't think that display is valid under the conditions you describe. Of course we don't know the conditions under which the picture was taken.

Don

That is what I thought.
I'm guessing that the LCD was not powered down between the various tests.

bperrybap:
That is what I thought.
I'm guessing that the LCD was not powered down between the various tests.

Oh yes, I switched the USB cable off each time.