/*******************************************************************************

  LCD_DISPLAY.h

  Displays Character string on LCD display module
  4 bit mode


*******************************************************************************/

#include "iom16c62p.h"

#define RS_PIN               p2_0  /* RS Register Select pin */
#define EN_PIN               p2_1  /* Display Enable pin */
#define DATA_PORT            p2    /* Data bus port */
#define DATA_PORT_MASK       0xF0  /* Bit mask from entire port */
#define DATA_PORT_SHIFT      4     /* Number of bits data needs to shift */
#define DATA_WR              1
#define CTRL_WR              0

#define DELAY_TIMING          0x01  /* Set to ensure base delay of 1mS minimum */
#define NUMB_CHARS_PER_LINE   8     /* number of lines on the LCD display */
#define MAXIMUM_LINES         2     /* Maximum charactors per line of LCD display. */
#define LCD_LINE1             0
#define LCD_LINE2             16

#define LCD_CLEAR             0x01  /* Clear LCD display and home cursor */
#define LCD_HOME_L1           0x80  /* move cursor to line 1 */
#define LCD_HOME_L2           0xC0  /* move cursor to line 2 */
#define CURSOR_MODE_DEC       0x04  /* Cursor auto decrement after R/W */
#define CURSOR_MODE_INC       0x06  /* Cursor auto increment after R/W */
#define FUNCTION_SET          0x28  /* Setup, 4 bits,2 lines, 5X7 */
#define LCD_CURSOR_ON         0x0E  /* Display ON with Cursor */
#define LCD_CURSOR_OFF        0x0C  /* Display ON with Cursor off */
#define LCD_CURSOR_BLINK      0x0D  /* Display on with blinking cursor */
#define LCD_CURSOR_LEFT       0x10  /*Move Cursor Left One Position */
#define LCD_CURSOR_RIGHT      0x14  /* Move Cursor Right One Position */
#define LCD_DISPLAY_ON        0x04
#define LCD_TWO_LINE          0x08
#define SET_BIT_HIGH          1
#define SET_BIT_LOW       0

void InitialiseDisplay( void );
void DisplayString(unsigned char position, char *string);
void LCD_write(unsigned char data_or_ctrl, unsigned char value);
void LCD_nibble_write(unsigned char data_or_ctrl, unsigned char value);
void DisplayDelay(unsigned long int units);


/*****************************************************************************
Name:           InitialiseDisplay
Description:    Intializes the LCD display.
*****************************************************************************/

void InitialiseDisplay( void )
{
    pd2=0xFF;  //Sets port P2 to output
        /* Power Up Delay for LCD Module */
    EN_PIN = SET_BIT_HIGH;
    DisplayDelay(7000);
    EN_PIN = SET_BIT_LOW;

    /* Display initialises in 8 bit mode - so send one write (seen as 8 bit)
    to set to 4 bit mode. */
    /* Function Set */
    LCD_nibble_write(CTRL_WR,0x03);
    //LCD_nibble_write(CTRL_WR,0x03);
    DisplayDelay(39);

    /* Configure display */
    //LCD_nibble_write(CTRL_WR,0x03);
    LCD_nibble_write(CTRL_WR,0x02);
    LCD_nibble_write(CTRL_WR,(LCD_DISPLAY_ON | LCD_TWO_LINE ));
    LCD_nibble_write(CTRL_WR,(LCD_DISPLAY_ON | LCD_TWO_LINE ));
    DisplayDelay(39);

    /* Display ON/OFF control */
    LCD_write(CTRL_WR,LCD_CURSOR_BLINK);
    DisplayDelay(39);

    /* Display Clear */
    LCD_write(CTRL_WR,LCD_CLEAR);
    DisplayDelay(1530);

    /* Entry Mode Set */
    LCD_write(CTRL_WR,0x06);
    LCD_write(CTRL_WR,LCD_HOME_L1);
}

/*****************************************************************************
Name:           DisplayString
Parameters:     position    Line number of display
                string      Pointer to data to be written to display.
                            Last character should be null.
Returns:        none
Description:    This function controls LCD writes to line 1 or 2 of the LCD.
                You need to use the defines LCD_LINE1 and LCD_LINE2 in order
                to specify the starting position.
                For example, to start at the 2nd position on line 1...
                   DisplayString(LCD_LINE1 + 1, "Hello")
*****************************************************************************/
void DisplayString(unsigned char position,  char *string)
{
    static unsigned char next_pos = 0xFF;

    /* Set line position if needed. We don't want to if we don't need
       to because LCD control operations take longer than LCD data
       operations. */
    if( next_pos != position)
    {
        if(position < LCD_LINE2)
        {
            /* Display on Line 1 */
            LCD_write(CTRL_WR, (unsigned char)(LCD_HOME_L1 + position) );
        }
        else
        {
            /* Display on Line 2 */
            LCD_write(CTRL_WR, (unsigned char)(LCD_HOME_L2 + position - LCD_LINE2) );
        }
        /* set position index to known value */
        next_pos = position;
    }

    do
    {
        LCD_write(DATA_WR,*string++);
        /* increment position index */
        next_pos++;
    }
    while(*string);


}

/*****************************************************************************
Name:           LCD_write
Parameters:     value - the value to write
                data_or_ctrl - To write value as DATA or CONTROL
                                1 = DATA
                                0 = CONTROL
Returns:        none
Description:    Writes data to display. Sends command to display.
*****************************************************************************/
void LCD_write(unsigned char data_or_ctrl, unsigned char value)
{
    /* Write upper nibble first */
    LCD_nibble_write(data_or_ctrl, (value & 0xF0) >> 4);
    /* Write lower nibble second */
    LCD_nibble_write(data_or_ctrl, (value & 0x0F));
}

/*****************************************************************************
Name:           LCD_nibble_write
Parameters:     value - the value to write
                data_or_ctrl - To write value as DATA or CONTROL
                                1 = DATA
                                0 = CONTROL
Returns:        none
Description:    Writes data to display. Sends command to display.
*****************************************************************************/
void LCD_nibble_write(unsigned char data_or_ctrl, unsigned char value)
{
    unsigned char ucStore;
    /* Set Register Select pin high for Data */
    if (data_or_ctrl == DATA_WR)
    {
        RS_PIN = SET_BIT_HIGH;
    }
    else
    {
        RS_PIN = SET_BIT_LOW;
    }
    /* There must be 40ns between RS write and EN write */
    DisplayDelay(1);
    /* EN enable chip (HIGH) */
    EN_PIN = SET_BIT_HIGH;
    /* Tiny delay */
    DisplayDelay(1);
    /* Clear port bits used */
    ucStore = DATA_PORT;
    ucStore &= ~DATA_PORT_MASK;
    /* OR in data */
    ucStore |= ((value << DATA_PORT_SHIFT) & DATA_PORT_MASK );
    /* Write data to port */
    DATA_PORT = ucStore;
    /* write delay while En High */
    DisplayDelay(20);
    /* Latch data by dropping EN */
    EN_PIN = SET_BIT_LOW;
    /* Data hold delay */
    DisplayDelay(20);
    if (data_or_ctrl == CTRL_WR)
    {
        /* Extra delay needed for control writes */
        DisplayDelay(0x7FF);
    }
}
/*****************************************************************************
Name:          DisplayDelay
Parameters:    units - Approximately in microseconds
Returns:       none
Description:   Delay routine for LCD display.
*****************************************************************************/
void DisplayDelay(unsigned long int units)
{
    unsigned long counter = units * DELAY_TIMING;
    while(counter--)
    {
        asm("nop");
    }
}