/*----------------------------------------------------------------------------------*/
/* File Name: Main
/* Processor: 87C752
/* ToolChain: Keil C51 V8.0
/* Author	: T.L
/* Version	: 1.0
/* Date		: 08/22/06 
/*----------------------------------------------------------------------------------*/

#pragma code
#pragma aregs
#pragma db

#include <Reg752.h>
#include <stdio.h>

/*----------------------------------------------------------------------------------*/
/* Global Constants
/*----------------------------------------------------------------------------------*/

#define	SysClk		12000000				// 12MHz
#define True		1
#define	False		0
#define Lcd			P3

sbit Rs =			P0^0;
sbit Rw =			P0^1;					
sbit En =			P0^2;

/*----------------------------------------------------------------------------------*/
/* Function prototypes
/*----------------------------------------------------------------------------------*/
void Main (void);
void Lcd_Init (void);
void Lcd_Cmd (unsigned char Cmd);
void Lcd_Dat (unsigned char Dat);
void Delay_mS (unsigned int mS);
void Delay_uS (unsigned int uS);
/*----------------------------------------------------------------------------------*/
/* Global Variables
/*----------------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------------*/
/* Main Routine
/*----------------------------------------------------------------------------------*/

void Main (void)
{
	P0 = 0xff;				//Use P0 lower nibble for Lcd Ctrl
	P1 = 0xff;
	P3 = 0xf0;				//Use P3 lower nibble for Lcd Data
	Lcd_Init ();
	Delay_mS (5);				//Delay 5ms

	while (1)
	{
		Lcd_Dat (0x41);			//Test character
		Delay_mS (5);			//Delay 5ms
	}
}

/*----------------------------------------------------------------------------------*/

void Lcd_Init (void)
{
	unsigned char i;
	i = 3;

	while (i)
	{
		Lcd_Cmd (0x28);			//2 line 4 bit
		Lcd_Cmd (0x0f);			//Display, Cursor, and blink on
		Lcd_Cmd (0x06);			//Increment, no shift
		i--;
	}
	Lcd_Cmd (0x01);				//Clear Lcd
	Delay_mS (2);				//Some delay
}

/*----------------------------------------------------------------------------------*/

void Lcd_Cmd (unsigned char Cmd)
{	
	Rs = 0;
	Rw = 0;
	En = 1;
	Lcd = (Cmd & 0xf0) >> 4;		//Write high nibble
	En = 0;
	En = 1;
	Lcd = (Cmd & 0x0f);			//Write low nibble
	En = 0;
	Delay_uS (50); 				//Delay 50us
}

/*----------------------------------------------------------------------------------*/

void Lcd_Dat (unsigned char Dat)
{
	Rs = 1;
	Rw = 0;
	En = 1;
	Lcd = (Dat & 0xf0) >> 4;		//Write high nibble
	En = 0;
	En = 1;
	Lcd = (Dat & 0x0f);			//Write low nibble
	En = 0;
	Delay_uS (50);				//Delay 50us
}

/*----------------------------------------------------------------------------------*/

void Delay_mS (unsigned int mS)
{
	unsigned int  i;
	for (i = 0; i < mS; i++);
	{
		TH = -(SysClk/12/1000) >> 8;	//Overflow @ 1ms 
		TL = -(SysClk/12/1000);		//	
		TR = 1;				// Start Timer0

	while (!TF);				// Poll overflow flag
		TR = 0;				// Stop Timer0
		TF = 0;				// Clear flag
	}
}

/*----------------------------------------------------------------------------------*/

void Delay_uS (unsigned int uS)
{
		TH = -uS >> 8;			//
		TL = -uS;			//
		TR = 1;				// Start Timer0

	while (!TF);				// Poll overflow flag
		TR = 0;				// Stop Timer0
		TF = 0;				// Clear flag
	
}

/*----------------------------------------------------------------------------------*/