#include <lpc21xx.h>

#define buzz 1<<25 /*lcd rs pin*/

#define pin_rs 1<<21 /*lcd rs pin*/

#define pin_rw 1<<23 /*lcd rw pin*/

#define pin_en 1<<20 /*lcd en pin*/

#define pin_ctrl pin_rs|pin_rw|pin_en /*lcd control pins. pin_ctrl include all 4 [pin_rs, pin_rw, pin_en]*/

#define lcd_d4 1<<16 /*lcd data pins D4,D5,D6,D7*/

#define lcd_d5 1<<17

#define lcd_d6 1<<18

#define lcd_d7 1<<19

#define lcd_data lcd_d4|lcd_d5|lcd_d6|lcd_d7 /*lcd_data include all 4 [lcd_d4, lcd_d5, lcd_d6, lcd_d7]*/

#define lcd_rs(x) ((x)?(IOSET1 = pin_rs):(IOCLR1 = pin_rs));  /*lcd_rs(x) if x=1 will set the lcd_rs pin will clear if x=0*/

#define lcd_rw(x) ((x)?(IOSET1 = pin_rw):(IOCLR1 = pin_rw));  /*lcd_rw(x) if x=1 will set the lcd_rs pin will clear if x=0*/

#define lcd_en(x) ((x)?(IOSET1 = pin_en):(IOCLR1 = pin_en));  /*lcd_en(x) if x=1 will set the lcd_rs pin will clear if x=0*/

#define data_in ((IOPIN0>>10)&(0x0F)) /*direction of the data pins as input*/

#define data_out(x) IOCLR0 = lcd_data; IOSET0 = (x & 0x0F)<<10; /*direction of the data pins and control pins as output*/

#define lcd_all_dir_out IODIR0 |= lcd_data ; IODIR1 |= pin_ctrl; /*setting as output for both data and control pins*/

#define lcd_dir_data_out IODIR0 |= lcd_data     /*set*/

#define lcd_dir_data_in IODIR0 &= ~(lcd_data)   /*clear*/

#define lcd_clear lcd_cmd_write(0x01);

static void delay(int);

static void delay(int cnt)

{

  cnt <<= 4;

  while(cnt--);   //delay

}

static unsigned char busy_wait()

{

  unsigned char (status);

  do

  {

    lcd_dir_data_in;//set pins as inputs

    lcd_rs(0);  // rs=0 indecates that data is being passed

    lcd_rw(1);  // rw=0 indicates that Read function is enabled

    lcd_en(1);  //enabeled

    delay(10);

    status = (data_in << 4)&(0xF0); //data_in shift by 4 AND 0xF0

    lcd_en(0);  //disabled

    delay(10);

    lcd_en(1);  //enabeled

    delay(10);

    status |= data_in; //bit wise OR

    lcd_en(0);  //disabled

    lcd_dir_data_out;  //set pins as outputs

    delay(10);

  }

  while(status & 0x80);  //bit wise AND

  return (status);

}

void lcd_write_4bit(unsigned char c)

{

  lcd_rw(0);  // rw=0 indicates that Read function is enabled

  lcd_en(1);  // enables the lcd

  data_out(c & 0x0F);//bit wise AND

  data_out(c);

  delay(10);

  lcd_en(0);

  delay(10);

}

static void lcd_cmd_write(unsigned char c)

{

  busy_wait();

  lcd_rs(0); // 0 indecates that data is being passed

  delay(10);

  lcd_write_4bit(c >> 4);// c is shifted to the right by 4 and passed to lcd_write_4bit() 

  lcd_write_4bit(c);  // c is passed to lcd_write_4bit()

}

static void lcd_data_write(unsigned char c)

{

  busy_wait(); //

  lcd_rs(1);  // 1 indecates that a command is being passed

  delay(10);

  lcd_write_4bit(c >> 4);// c is shifted to the right by 4 and passed to lcd_write_4bit() 

  lcd_write_4bit(c); // c is passed to lcd_write_4bit()

}

static void lcd_init()

{

  lcd_all_dir_out; //set pins as outputs

  delay(10);

  lcd_rs(0);       // 0 indecates that data is being passed

  lcd_write_4bit(0x3);

  delay(10);

  lcd_write_4bit(0x3);

  delay(10);

  lcd_write_4bit(0x3);

  lcd_write_4bit(0x2);

  lcd_cmd_write(0x28); // 1 01000 = 1[(0)DL (1)N (0)F (0)* (0)*]   Sets interface data length (DL) number of display lines (L) and character font(F).

  lcd_cmd_write(0x0C); // 1 100 = 1[(1)Disp (0)Cursor (0)Blink] display ON curser OFF   blink OFF

  lcd_cmd_write(0x06); // courser auto increment

}

void lcd_print(unsigned char const *mess)

{

  while(*mess)

  {

    lcd_data_write(*mess++);//repeats this function for every constant in string mess

  }

}

int main(void)

{  

  PINSEL2 &= 0x0;//SET IO PORT FUNCTIONALITY

  IODIR1 = 0xFFFF; //set all as outpuT

  delay(1000);

  lcd_init();    //initilize lcd

  lcd_clear;    //clears lcd

  lcd_print("test");   //used for testing

  delay(1000);

while(1);

}