Text Direction methods leftToRight() and rightToLeft()

The Liquid Crystal Library allows you to control LCD displays that are compatible with the Hitachi HD44780 driver. There are many of them out there, and you can usually tell them by the 16-pin interface.

This example sketch shows how to use the leftToRight() and rightToLeft() methods. These methods control which way text flows from the cursor.

rightToLeft() causes text to flow to the left from the cursor, as if the display is right-justified.

leftToRight() causes text to flow to the right from the cursor, as if the display is left-justified.

This sketch prints a through l right to left, then m through r left to right, then s through z right to left again.

Hardware Required

  • Arduino or Genuino Board
  • LCD Screen (compatible with Hitachi HD44780 driver)
  • pin headers to solder to the LCD display pins
  • 10k ohm potentiometer
  • 220 ohm resistor
  • hook-up wires
  • breadboard

Circuit

Before wiring the LCD screen to your Arduino or Genuino board we suggest to solder a pin header strip to the 14 (or 16) pin count connector of the LCD screen, as you can see in the image above.
To wire your LCD screen to your board, connect the following pins:

  • 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

Additionally, wire a 10k pot to +5V and GND, with it's wiper (output) to LCD screens VO pin (pin3). A 220 ohm resistor is used to power the backlight of the display, usually on pin 15 and 16 of the LCD connector

click the images to enlarge

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Schematic

click the images to enlarge

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Code

/*
LiquidCrystal Library - TextDirection

Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
library works with all LCD displays that are compatible with the
Hitachi HD44780 driver. There are many of them out there, and you
can usually tell them by the 16-pin interface.

This sketch demonstrates how to use leftToRight() and rightToLeft()
to move the cursor.

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)

Library originally added 18 Apr 2008
by David A. Mellis
library modified 5 Jul 2009
by Limor Fried (http://www.ladyada.net)
example added 9 Jul 2009
by Tom Igoe
modified 22 Nov 2010
by Tom Igoe

This example code is in the public domain.

http://www.arduino.cc/en/Tutorial/LiquidCrystalTextDirection

*/


// 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);

int thisChar = 'a';

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // turn on the cursor:
  lcd.cursor();
}

void loop() {
  // reverse directions at 'm':
  if (thisChar == 'm') {
    // go right for the next letter
    lcd.rightToLeft();
  }
  // reverse again at 's':
  if (thisChar == 's') {
    // go left for the next letter
    lcd.leftToRight();
  }
  // reset at 'z':
  if (thisChar > 'z') {
    // go to (0,0):
    lcd.home();
    // start again at 0
    thisChar = 'a';
  }
  // print the character
  lcd.write(thisChar);
  // wait a second:
  delay(1000);
  // increment the letter:
  thisChar++;
}

See Also



  • Hello World! – How to wire an LCD display and bring it to life.
  • Blink - Control of the block-style cursor.
  • Cursor - Control of the underscore-style cursor.
  • Display - Quickly blank the display without losing what's on it.
  • Scroll - Scroll text left and right.
  • Serial display - Accepts serial input, displays it.
  • SetCursor - Set the cursor position.
  • Autoscroll - Shift text right and left.


Last revision 2015/08/17 by SM

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