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Text LCD

Table of Contents

  1. Hello World!
  2. Text LCD Library
  3. Different LCD Panel Sizes
  4. Reference

A driver code library for Text LCD panels using the 4-bit HD44780 lcd display driver.

/media/uploads/simon/textlcd-helloworld.jpg

Hello World!

Import program
TextLCD_HelloWorld - main.cpp

00001 // Hello World! for the TextLCD
00002 
00003 #include "mbed.h"
00004 #include "TextLCD.h"
00005 
00006 TextLCD lcd(p15, p16, p17, p18, p19, p20); // rs, e, d4-d7
00007 
00008 int main() {
00009     lcd.printf("Hello World!\n");
00010 }
TextLCD pinsmbed pins
GND0V
VCC3.3V
VO0V, via 1k resistor
RSp15
RW0V
Ep16
D0not connected
D1not connected
D2not connected
D3not connected
D4p17
D5p18
D6p19
D7p20

Warning

The contrast VO pin seems to have different behaviour on different screens, so you may need to experiment for your screen to see anything. I think i've seen some work tied to 0v, some to 3.3v, or with a different resistor.

Text LCD Library

Import library
TextLCD - TextLCD Class Reference

Public Types

enum LCDType { LCD16x2 , LCD16x2B , LCD20x2 , LCD20x4 }

LCD panel format.

More...

Public Member Functions

TextLCD (PinName rs, PinName e, PinName d4, PinName d5, PinName d6, PinName d7, LCDType type=LCD16x2)
Create a TextLCD interface.
int putc (int c)
Write a character to the LCD.
int printf (const char *format,...)
Write a formated string to the LCD.
void locate (int column, int row)
Locate to a screen column and row.
void cls ()
Clear the screen and locate to 0,0.

Different LCD Panel Sizes

Setting the type field int the TextLCD constructor allows configuration for the different display panel sizes:

TextLCD::LCD16x2     16x2 LCD panel (default) 
TextLCD::LCD16x2B    16x2 LCD panel alternate addressing 
TextLCD::LCD20x2     20x2 LCD panel 
TextLCD::LCD20x4     20x4 LCD panel

For example:

#include "mbed.h"
#include "TextLCD.h"

TextLCD lcd(p15, p16, p17, p18, p19, p20, TextLCD::LCD20x4); // rs, e, d4-d7

int main() {
    lcd.printf("Hello World!\n");
}

Reference

The underlying HD44780 chip is a driver used in many LCD character displays. It might sometimes be referred to as Hitachi HD44780U.

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