LCD Library for ARM LPC2148

LCD Library for ARM

Liquid Crystal Display also called as LCD is very helpful in providing user interface as well as for debugging purpose. A liquid crystal display (LCD) is a flat panel display that uses the light modulating properties of liquid crystals (LCs). LCD Modules can present textual information to user.

                    A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. Click to learn more about internal structure of a LCD.

LCD Open source Header file provides a library for communication with LCDs  through the 4-bit interface. An example of LCD connections is given on the schematic at the bottom of this page.

Note: ARM development system based initialization routines are included in lcd.h.So just  add this header file to  your source code for accessing the LCD  

Note: LCD_Config needs RW for checking the LCD busy and this is tested for LPC2148

Library Routines

• LCD_Config
• LCD_Out
• LCD_Out_Cp
• LCD_Chr
• LCD_Chr_Cp
• LCD_Cmd

LCD_Config

Prototype	void LCD_Config(unsigned short *Dport, unsigned short *port, unsigned short RS, unsigned short EN, unsigned short WR, unsigned short D7, unsigned short D6, unsigned short D5, unsigned short D4);
Returns	Nothing.
Description	Initializes LCD at port with pin settings you specify: parameters RS, EN, WR, D7 .. D4 need to be a combination of values 0–7 (e.g. 3,6,0,7,2,1,4).
Requires	Nothing.
Example	LCD_Config(&IODIR1, &IOPIN1, 0, 1, 7, 5, 4, 3, 2);

LCD_Out

Prototype	void LCD_Out(unsigned short row, unsigned short col, char *text);
Returns	Nothing.
Description	Prints text on LCD at specified row and column (parameters row and col). Both string variables and literals can be passed as text.
Requires	Port with LCD must be initialized. See LCD_Config.
Example	Print “Hello!” on LCD at line 1, char 3: LCD_Out(1, 3, "Hello!");

LCD_Out_Cp

Prototype	void LCD_Out_Cp(char *text);
Returns	Nothing.
Description	Prints text on LCD at current cursor position. Both string variables and literals can be passed as text.
Requires	Port with LCD must be initialized. See LCD_Config.
Example	Print “Here!” at current cursor position: LCD_Out_Cp("Here!");

LCD_Chr

Prototype	void LCD_Chr(unsigned short row, unsigned short col, char character);
Returns	Nothing.
Description	Prints character on LCD at specified row and column (parameters row and col). Both variables and literals can be passed as character.
Requires	Port with LCD must be initialized. See LCD_Config.
Example	Print “i” on LCD at line 2, char 3: LCD_Chr(2, 3, 'i');

LCD_Chr_Cp

Prototype	void LCD_Chr_Cp(char character);
Returns	Nothing.
Description	Prints character on LCD at current cursor position. Both variables and literals can be passed as character.
Requires	Port with LCD must be initialized. See LCD_Config.
Example	Print “e” at current cursor position: LCD_Chr_Cp('e');

LCD_Cmd

Prototype	void LCD_Cmd(unsigned short command);
Returns	Nothing.
Description	Sends command to LCD. You can pass one of the predefined constants to the function. The complete list of available commands is below.
Requires	Port with LCD must be initialized. See LCD_Config.
Example	Clear LCD display: LCD_Cmd(LCD_Clear);

Available LCD Commands

LCD Command	Purpose
LCD_FIRST_ROW	Move cursor to 1st row
LCD_SECOND_ROW	Move cursor to 2nd row
LCD_THIRD_ROW	Move cursor to 3rd row
LCD_FOURTH_ROW	Move cursor to 4th row
LCD_CLEAR	Clear display
LCD_RETURN_HOME	Return cursor to home position, returns a shifted display to original position. Display data RAM is unaffected.
LCD_CURSOR_OFF	Turn off cursor
LCD_UNDERLINE_ON	Underline cursor on
LCD_BLINK_CURSOR_ON	Blink cursor on
LCD_MOVE_CURSOR_LEFT	Move cursor left without changing display data RAM
LCD_MOVE_CURSOR_RIGHT	Move cursor right without changing display data RAM
LCD_TURN_ON	Turn LCD display on
LCD_TURN_OFF	Turn LCD display off
LCD_SHIFT_LEFT	Shift display left without changing display data RAM
LCD_SHIFT_RIGHT	Shift display right without changing display data RAM

Example:

#define CCLK     60           //System Frequency should mentioned for LCD

#define lcd_port IOPIN1                 //LCD Port

#define lcd_port_direction         IODIR1  //LCD Direction Port

#include <lpc214x.h>

#include <stdio.h>

#include "lcd.h"                  //LCD Header Files

char *name1 = "Hitech Solutions";

char *name2 = "JAA EmbeddedPark";

void Enable_PLL()

{

PLL0CFG &=~(0x7F);       //For clear 0t06

PLL0CFG |=0x04;                              //External OSC 12MHZ so 60/12 =5-1=4

PLL0CFG |=0x01<<5;      //Multipler and divider setup

PLL0CON=0x01;                //Enable PLL

PLL0FEED=0xAA;              //Feed sequence

PLL0FEED=0x55;

while(!(PLL0STAT & 0x0400)); //is locked?

PLL0CON=0x03;                //Connect PLL after PLL is locked

PLL0FEED=0xAA;              //Feed sequence

PLL0FEED=0x55;

}

int main()

{ 

Enable_PLL();

 LCD_Config(&lcd_port_direction,&lcd_port,16,18,17,22, 21, 20, 19);       //4bit LCD configuration

 LCD_Cmd(LCD_CLEAR);       // Clear display

 LCD_Cmd(LCD_CURSOR_OFF);  // Turn cursor off

 LCD_Out(1, 1, name1);      // Print text to LCD, 1nd row, 1st column

 LCD_Out(2, 1, name2);      // Print text to LCD, 2nd row, 1st column

               

 return(0);

}

Download LCD Header File                                                       Download Source Code for KEIL

 This all LCD functions in lcd.h