LCD 8-bit interface using "LCD Busy Flag"

/****************************************************************
Project : LCD 8-bit interface Test
Author  : kouchenan(amihomo) ([url]www.amihomo.persianblog.ir[/url])                             
Chip type           : ATmega8535
Clock frequency     : 4.000000 MHz
==========================================================
PORTC[0..7] ==>  DB0..DB7 LCD data bus (pin 14-pin7)
LCD EN (pin 6) ==> PORTD.7
LCD RW (pin 5) ==> PORTD.6
LCD RS (pin 4) ==> PORTD.5
               
*******************************************************************/

#include <mega8535.h>
#include <string.h>
#include <delay.h>
#define EN PORTD.7
#define RW PORTD.6
#define RS PORTD.5
#define BF PINC.7   //busy flag

/*****************************************************************************/
/* LCD Commands ( Refer to LCD Data Sheet )                                  */
/* Standard command should work with most common devices                     */
/*****************************************************************************/
/*                                                                           */
#define write_data        0x00 /* With RS = 1                                */
#define clr_lcd           0x01 /* Clear Display                              */
#define ret_home          0x02 /* Cursor to Home position                    */
#define entry_mode        0x06 /* Normal entry mode                          */
#define entry_mode_sh     0x07 /* - with shift                               */
#define sys_set_4_bit     0x28 /* 4 bit data mode 2 line ( 5x7 font )        */
#define sys_set_8_bit     0x38 /* 8 bit data mode 2 line ( 5x7 font )        */
#define disp_on           0x0C /* Display ON                                 */
#define disp_off          0x08 /* Cursor plus blink                          */
#define cursor_on         0x0E /* Switch Cursor ON                           */
#define cursor_on_blink   0x0F /* Switch Cursor ON ,Blink ON                 */
#define cursor_off        0x0C /* Switch Cursor OFF                          */
#define move_cursor_l     0x10 /* Move cursor one character left             */
#define move_cursor_r     0x14 /* Move cursor one character right            */
#define scrl_disp_l       0x18 /* Scroll display 1 character left (all lines)*/
#define scrl_disp_r       0x1E /* Scroll display 1 character left (all lines)*/ 
#define goto_line1        0x80 /* Line 1 position 1                          */
#define goto_line2        0xC0 /* Line 2 position 1                          */
/*****************************************************************************/
void waitLCD(void);
void writeLCD(unsigned char byte ,unsigned char rs); //rs=0 for commands, rs=1 for data
void putStr(unsigned char str[]);
void initLCD(void);
void gotoXY(unsigned char x ,unsigned char y);
//=====================================================
void main(void)
{
   char msg[]="Hello World!This is an LCD test!";
   DDRC=0xff;
   PORTC=0xff;   //Set all data pins to 1 initially
   DDRD=0xff;

   initLCD();
   
   putStr(msg);
   
   while (1)
   {
      //loop forever                  
   }
}

void initLCD(void)
{   
   //delay_ms(45);
   writeLCD(sys_set_8_bit,0);
   writeLCD(cursor_on_blink,0);
   writeLCD(clr_lcd,0);
   writeLCD(entry_mode,0);
}

void writeLCD(unsigned char byte ,unsigned char rs)
{
   DDRC=0xff;
   PORTC=byte;
   RS=rs;   //rs=0 for commands, rs=1 for data
   RW=0;
   EN=1;
   EN=0;
   waitLCD();
}
//monitor the busy flag of LCD on its DB7
void waitLCD(void)
{

   unsigned char busy=1;
   //unsigned char cnt=0;
   do
   {
      DDRC=0xff;
      PORTC=0xff;   //Set all data pins to 1 initially
       DDRC=0x00;   //configure all bits as inputs
      EN=0;      //Start LCD command
      RS=0;      //It's a command
      RW=1;      //It's a read command
      EN=1;
      busy=BF;   //read the busy flag
      //cnt++;
      
   } while(busy==1);// && cnt<255);
   EN=0;   //Finish the command
   RW=0;   //Turn off RW for future commands

   
}

void putStr(unsigned char str[])
{
   unsigned char i;
   for (i=0;i<strlen(str);i++)
   {
      if (i>15)
         gotoXY(1,i-16);
      writeLCD(str[i],1);
   }
}

 
 
void gotoXY(unsigned char x ,unsigned char y)
{
   //x is 0 or 1
   //y is between 0 and 0x0f
   unsigned char pos;
   pos=x ? (0x80+0x40+y):(0x80+y) ;
   
   DDRC=0xff;
   PORTC=pos;
   RS=0;
   RW=0;
   EN=1;
   EN=0;
   waitLCD();   
}