I started using an 16x2 LCD today. But the problem is i sometimes i have to upload the code many times. Why i have to do this is because i get wierd symbols in the display on some uploads.
For example, one time i might try to display "Hello" and would get "QD4" or something like that. So i upload a few more times and after some attempts it works.
Anyone know what it could be?
Im pretty sure i wired it correctly, and it is working "most of the time"
If i upload this code to my arduino:
#Include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void Setup() {
delay(1000); // Added delay to make sure lcd is powered
lcd.begin(16, 2);
lcd.print("Hello World");
}
void Loop() {
}
Sometimes i will get “Hello World” on the screen.
Other times ill get strange signs.
And i dont even have to reupload for this to happen.
If i just press the “reset button” on the arduino.
It will flip between “Hello World” and “Strange Signs” (always the same strange signs)
Sometimes it might be “Hello World” a few times in a row when resetting.
And sometimes the signs.
Im stumped 
Ok, now you have this connected to a relay, don’t you? 
That was the critical detail. Common problem.
Connect a 47 or 100 µF capacitor between pins 1 and 2 of the LCD.
Not sure what a relay is :P
Really i need a capacitor? How come its not used here: https://www.arduino.cc/en/uploads/Tutorial/LCD_Base_bb_Schem.png
How come its not used here:
Because there is no inductive load such as a relay or a motor or a pump in that circuit.
The code in your original post most likely works all the time since there is no pump involved.
I didn’t see any evidence of the words “Hello World” in your video which obviously uses different code as well as additional hardware – something you neglected to mention.
Don
Oh i dont use a pump or anything like that. I just used the video to show what symbols i got.
Was not my video, so its abit misleading. Sorry.
Im just doing the Hello World text.
Let's start again. We need to see:
Don
A photograph of your actual setup. A copy/paste version of the code that you are actually using. A photograph of the characters that are actually being displayed by the above mentioned hardware and software.
Ok here we go, this is the schema im using:
This is the setup:
These two pictures are using the exact same code!
The only diffrence is i pressed reset.
So the reset or reupload will toggle between these states.
Oh and here is the code:
#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
lcd.begin(16, 2);
lcd.print("Hello World!");
}
Hmmm.
This is the classic "nibble shift" fault.
Suggest you re-solder the "E" connection on the LCD - and check the continuity of that wire to the Arduino.
The 'nibble shift' problem is likely due to a somewhat out of spec LCD controller and will probably not be fixed by tinkering with the wiring (other than by adding four more wires and using an 8-bit interface).
Your display will probably work if you use a library that is designed to deal with these low quality displays. One such library was actually written for 40x4 displays but will work with your 16x2.
To get a copy start here:--> http://code.google.com/p/liquidcrystal440/ and follow the [u]Downloads[/u] link to get to the latest version.
Don
I have tried using liquidcrystal440 but i cant fix the code.
First it gave me error of a return type not being the same as the overriden version.
I managed to fix that error.
But then i got errors that WProgram.h could not be found.
BTW, clear the LCD screen after lcd.begin
.
LarryD: BTW, clear the LCD screen after lcd.begin
.
I tried that..
LarryD: BTW, clear the LCD screen after lcd.begin
.
Why?
Don
Gobaz: I have tried using liquidcrystal440 but i cant fix the code. First it gave me error of a return type not being the same as the overriden version. I managed to fix that error. But then i got errors that WProgram.h could not be found.
I don't think that you followed the downloads link to get to the latest version since the updated program is NOT called 'liquidcrystal440'.
Don
floresta:
I don’t think that you followed the downloads link to get to the latest version since the updated program is NOT called ‘liquidcrystal440’.Don
Ahh ok thanks.
I downloaded the latest version now.
And i tested it, there was no change, same behavior.
Have you tried the 8-bit mode? Note: You will have to use the original library to do this since the liquidcrystal440 library and it's successor do not support the 8-bit mode.
Don