LCD 1602A, Solved!

Hi, Guys.
Today my friend's got a problem when he tried to connect LCD 1602A to a Arduino Mega260 board. He asked me "Why LCD did not show anything?". So I tried to find some topics to help him. Some guys solved this problem, and update into forum but sometimes we did, but we don't understand why we did, how does it work...

Defested:
Problem has been solved! I do not know what the problem was, after unwiring everything and rewiring with new Arduino, breadboard, and wire it works now.

I did it too. And I hope this topic help you solve your problems with LCD 1602A (Figure 1 - Try to connect!)

First of all, I used both Uno and Mega 2650; LCD 1602A, and two potentiometers 10KOhm; wires and breadboard.
Instead of using resistors (I don't know exactly how much resistor we need), try to connect LCD 1602A to Arduino board uses two potentiometers 10kOhm as figure bellow. I'm sure you know how to connect them.

The circuit:

  • LCD RS pin to digital pin 12
  • LCD Enable pin to digital pin 11
  • LCD D4 pin to digital pin 5
  • LCD D5 pin to digital pin 4
  • LCD D6 pin to digital pin 3
  • LCD D7 pin to digital pin 2
  • LCD R/W pin to ground
  • ends to potentiometer signal pin and ground
  • wiper to LCD VO pin (pin 3)


Figure 2 _ Connection diagram!
If we use two potentiometers, we can adjust bright on LCD and what we want to show.
Anode - Pin 15 (A) adjusts bright on LCD
V0 - Pin 3 adjusts contrast of light as far as I understand;
Now you can try to upload sample programs from File> Examples> LiquidCrystal> ....
And here is my result, You can do it.

Figure 3 - Result

// 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("Well done.");
  
  lcd.setCursor(0, 1);
  lcd.print("We did it!");
}

void loop() {
}

Well done!

My first time on Forum, I don't know how to show images in post although I used tool "Insert an image",

I'm sure you know how to connect them.

I hope so too . . . because your diagram is incorrect!

Don

floresta:
I hope so too . . . because your diagram is incorrect!

Don

Hi Don,
Thanks for your feedback!
This is my first time with LCD 16x2, I looked back my diagram and tried connect again, I don't understand why it's incorrect. Could you help me correct it? please,
Thank you, Mr Don.

How is the backlight receiving power?

Don

floresta:
How is the backlight receiving power?

But at least it is very well grounded... :wink:

Hi Don and bperrybap,
I don't know exactly how much resister is, therefore I used potentiometer 2 to control power input for pin 15 as far as I understand. Both simulation and real model showed result.

link_tran:
I used potentiometer 2 to control power input for pin 15 as far as I understand.

What Don and I are saying, is that in the connection diagram you posted, there is no power going to the pot and hence to pin 15.
And that is why, if your backlight is working, the connection diagram is wrong and does not match how you have actually wired it up.

Not sure how the simulator works, but if it shows the backlight working (on) with that wiring, then it isn't a very good simulator.

--- bill