Change LCD Pins on Mega

Other Hardware Displays
1

Hello I have a arduino Mega board that I am using to control my preamp. I just started learning arduino and programing and need bit of help. I have a 4x20 LCD HD44780 screen and I want to change the default pin outs on the arduio to run it. I have heaps of spare pins as Im using a mega. It wants to run on pins 12, 11, 5, 4, 3, 2. these pins are in use for something else (rotary encoder and pga2310 volume controller) How do I change the pin outs??

Thank you in advance for your help

2

Thanks for the fast reply :smiley:

How Do I change the pin definitions in the LCD library, I cant find an reference to pin numbers in the LCD lib files. I tried moving the encoder and it wont work, think its something to do with the way it uses interrupts, I used the standard encoder code from the playground. Sorry for all the questions but I am still new to this. Thanks for your help ?

3

If you are using the LiquidCrystal library functions, you just specify the pins you want to use in the initial setup. Here is from a example partial code, (just showing setup function) file in the library:

// 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); // here is where you tell it what pins you want to use
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!");
}

Here are the what the standard pin numbers are called and the function they perform for the display:

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
  • 10K resistor:
  • ends to +5V and ground
  • wiper to LCD VO pin (pin 3)
4

Thank you so much for your help. It works great :slight_smile: