LCD Display not working

Ive seen a bunch of these but my issue seems to be different. The LED lights up, I can see only 1 row of blocks at the top. If I play with the contrast I see those blocks disappear and reappear, but just as blocks, no hello world words.

Here is my code:

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis() / 1000);

Ive got it set up as the tutorial here states:



1 -------------- GROUND
2 -------------- 5V
3 -------------- POT SIGNAL
4 -------------- 12 DIGITAL
5 -------------- GROUND
6 -------------- 11 DIGITAL
7 --------------
8 --------------
9 --------------
11------------- 5 DIGITAL
12------------- 4 DIGITAL
13------------- 3 DIGITAL
14------------- 2 DIGITAL
15------------- 5V (without resistor because i have R8 & R9 in the back of the LCD board)
16------------- GROUND

Here is the picture of what it all looks like:

I can't see anything wrong. Double check your wiring. Then, add some code to flash the LED on pin 13 just to make sure the code got uploaded correctly and is running. (there's a hint there)

Well I originally have a Serial.begin(9600); and a Serial.println("Hello"); in the past few lines of the setup() and those log out fine. I just checked it again and its working...I put a println in the setup and another one after a delay in the loop and both are working.

I also tapped the reset button on the arduino board.

Could it be my soldering job?

This is the first time Ive ever done it. :smiley:

What the beep happened there ?

Yes, it's the soldering. Don't give up the dayjob yet. The solder is everywhere except where it needs to be. Remove all solder, and try again. I'm sorry but i've never seen something like that and i really can't tell what you did to get that result.

Oh, wait a moment. Did you just heat the pins and apply solder ? Try heating the pin and pad at the same time and then apply a bit of solder. Make sure there are no solder connections between any pads. Just need to connect one single pin to one single pad.

:sweat_smile: :sweat_smile: :sweat_smile: :sweat_smile: :sweat_smile:


Ok here is a better job.

I have an inappropriate soldering iron, apparently a brand called KMC but the problem is that its not a pointy tip like Ive seen on many electronics video but rather it has a tip that is like a curved loop. It goes out from the gun, loops around in a very closed loop and comes back. But its not good at making small drops, just bigger gobs.

That's a much better job, you're learning here. The soldering tool is a soldering gun. You need to press a trigger for it to heat up, and at that time a lightbulb will probably light up. The loopy ting is part of a single loop coil in a transformer, the other side of that is connected to the wall socket if you press the trigger. This solder gun really is the wrong tool for soldering delicate electronics, go get a better one. The "tip" which is none can't be placed correctly to do a good job, and it will get too hot too. Almost any other iron is better than such gun.

For now and from this angle the soldering is much improved.

VSS, VDD, RS and D3 look like they could be improved, still some of the pad visible.

OK it's working now. I'll look into getting a new solder thing. I found some on Amazon for $20.

Well, then well done.

Once you've got the new iron, practice a bit before doing projects. I can't see it very well in that last picture, but i think it's a bit rich on solder (that's still better than too little solder).

Wow, that first attempt at solder was amazing :o Much better the 2nd time. D6 and D7 look very good, so that is what you are going to try to get going forward. I would suggest you heat Vss again to get it to flow to the pad. The others are probably acceptable for now until you get a better iron. D3 and D4 are not shorted?

Get the best iron you can afford, you won’t regret it if you do much soldering.

Recommend any solders?

I'll test D3 and D4 to make sure.

Weller makes some good soldering irons. You can pick them up at most hardware stores. Haco makes good ones also, I've only seen them online, never local.

The kind with a stand and sponge are the best if you will be doing this much. Maybe buy a smaller tip than what comes with the soldering iron. They usually run about a dollar and it is money well spent.

Also look at picking up some liquid flux. It will make things quite a bit easier for you. LIGHTLY apply flux to the pad and to the leg, then put some solder on the tip, touch leg/pad, hold for a second. You'll see the solder 'flow' when you see that, take the tip off in a smooth motion. The 'flow' should take half a second to a second on these small guys, don't hold it there too long as you risk burning up the chip!

OK, I have saved those two images for future use! :astonished:

For this sort of work a soldering gun is OK - as long as you are experienced with using it. I grew up with the robust and vicious "Scope" irons - apparently they still make them. Good on 'em! - though they are absurdly expensive.

Of course I graduated to a Weller TCP-1 and have used this for a number of decades, though I am running short of spare parts and may need to buy some Chinese thing.

In any case, you still seem to have a problem on that last photo, with the VSS, D3 (which doesn’t matter) and possibly VDD pins.

Thanks Paul. You've been quite patient and very helpful.

I've already started looking at a few wellers and I'll fix that lcd as soon as I can.

Luckily I won't be using the LCD anytime soon. My project doesn't require one. What I'm hoping to work on is a few sensors (VOCs, CO, NO, Dust, T, Pressure, UV), a wifi or GPRS shield and a cloud database. I'm pretty sure there is a drone involved at some point and I have one I can hack, so that might require soldering but that's a few weeks down the line

Marciokoko: I've already started looking at a few Wellers and I'll fix that LCD as soon as I can.

Even a rough iron can be made to work with some skill (as long as it is not under-powered). The use of flux is probably the most critical matter. I have never used additional flux but probably should (only ever rosin-based). Finer gauge solder generally has more flux by proportion.

Marciokoko: I'm pretty sure there is a drone involved at some point and I have one I can hack, so that might require soldering but that's a few weeks down the line

I just bought a (single rotor) RC helicopter this morning for $20 from a garage sale in pretty much perfect condition (no marks on either fitted or spare blades and lights go on on either copter or transmitter when I turn on the power switch - always a critical sign when buying second hand stuff). That will keep me amused.

Your second attempt was much better than the first. I took electronics in high school and my soldering looked a lot like your second attempt and I thought I was doing pretty good. However, I went through micro/miniature repair school in the U.S. Marine Corps and learned how to solder to NASA standards and let me tell you, it hurts my eyes to look back at some of my high school projects. My point being, keep at it and watch some YouTube videos on how to solder. I'll give you some tips.

  1. Make sure that your surfaces are clean and free of dirt and especially strange coatings. In the Marines we used to have old school eraser pencils that were designed for erasing type writer mistakes(Eraser Pencil). They worked great for cleaning component leads.

We also used KimWipes with Isopropyl alcohol to clean any oil or other residue from the surfaces to be soldered.

Worst case, you'll have to actually scrape the stuff off the surface you want to solder.

  1. Use rosin flux along with the rosin core solder. You can buy rosin flux separately. We had little applicator bottles to put droplets of rosin flux right on the surface to be soldered. It makes a bit of a mess but use some isopropyl alcohol, acid brush and KimWipes to clean up the work area when you're finished.

  2. Use just enough solder to make a nice fillet. It should be concave (curving in towards the pin). Good solder joint.

  3. Don't over heat the solder pad. It can delaminate from the board and then you have to stick it back down with epoxy... and that's another lesson.

First of all you need to prove that the digital pins output in respective sequence, you may prove this by using proteus simulation with leds and in the similar way with your arduino compare the two.

Next use a two ohm resistor connected from your Vo pin of 16x2 lcd to ground. I just did so. at first I destroyed my first lcd thinking it had problems but it hadnt that was the problem.