/*     16x2 character LCD
 *     .----------------.
 *     |  pin15         |- unused
 *     |  pin16         |- unused
 *     |                |
 *     |  pin01      GND|- GND 
 *     |  pin02      +5v|- +5v 
 *     |  pin03 Contrast|- 4.7k pot 
 *     |  pin04       RS|- PORTB1
 *     |  pin05       RW|- GND 
 *     |  pin06       EN|- PORTB0
 *     |  pin07    Data0|- GND 
 *     |  pin08    Data1|- GND
 *     |  pin09    Data2|- GND
 *     |  pin10    Data3|- GND
 *     |  pin11    Data4|- PORTB4
 *     |  pin12    Data5|- PORTB5
 *     |  pin13    Data6|- PORTB6
 *     |  pin14    Data7|- PORTB7
 *     '-----------------'   
 *
 *  LCD interface.
 *  This code will interface to a standard LCD controller like the Hitachi HD44780.
 *  This code is for the standard 14 pin connector, and 4-bit mode is assumed.
 */

#include  <pic.h>
#include  "lcd.h"
#include  "delay.c"

static bit LCD_RS  @ ((unsigned)&PORTB*8+1);  // Register select
static bit LCD_EN  @ ((unsigned)&PORTB*8+0);  // Enable
#define	LCD_STROBE  ((LCD_EN = 1),(LCD_EN=0))

/* Clear and home the LCD. 
 */
void lcd_clear_and_home(void)
{
  LCD_RS = 0;
  lcd_write_byte(0x01);
  delay_ms(2);
}

/* Go to the specified position.
 */
void lcd_goto(unsigned char pos)
{
  LCD_RS = 0;
  lcd_write_byte(0x80+pos);
}

/* Write one byte to the LCD.
 */
void lcd_write_byte(unsigned char c)
{
  PORTB = (PORTB & 0x0F) | (c & 0xF0);
  LCD_STROBE;
  PORTB = (PORTB & 0x0F) | (c << 4);
  LCD_STROBE;
  delay_us(40);
}

/* Write one char to the LCD.
 */
void lcd_write_char(char c)
{
  LCD_RS = 1;  // characters
  PORTB = (PORTB & 0x0F) | (c & 0xF0);
  LCD_STROBE;
  PORTB = (PORTB & 0x0F) | (c << 4);
  LCD_STROBE;
  delay_us(40);
}

/* Write a string of chars to the LCD.
 */
void lcd_write_string(const char * s)
{
  LCD_RS = 1;  // characters
  while(*s)
  { lcd_write_byte(*s++); }
}

/* Clear and home the LCD,
 * then write a string of chars to the LCD.
 */
void lcd_overwrite_string(const char * s)
{
  lcd_clear_and_home();
  LCD_RS = 1;  // characters
  while(*s)
  { lcd_write_byte(*s++); }
}
	
/* Write a string of chars to the LCD 
 * starting at the beginning of the second line of the display.
 */
void lcd_write_string_at_second_line(const char * s)
{
  lcd_goto(64);
  LCD_RS = 1;  // characters
  while(*s)
  { lcd_write_byte(*s++); }
}

/* Initialise the LCD.
 */
void lcd_initialize(void)
{
  LCD_RS = 0;   // write control bytes
  delay_ms(15);  // power on delay
  PORTB = 0x30; // attention!
  LCD_STROBE;
  delay_ms(5);
  LCD_STROBE;
  delay_us(100);
  LCD_STROBE;
  delay_ms(5);
  PORTB = 0x20; // set 4 bit mode
  LCD_STROBE;
  delay_us(40);
  lcd_write_byte(0x28);  // 4 bit mode, 1/16 duty (2 lines), 5x8 dots
  lcd_write_byte(0x0C);  // display on, blink off, cursor off
//lcd_write_byte(0x0F);  // display on, blink on, cursor on
  lcd_write_byte(0x06);  // entry mode

  lcd_load_custom_characters();
}

/* Load the custom characters into cgram.
 * Also performs Clear and Home.
 */
void lcd_load_custom_characters(void)
{
  LCD_RS = 0;
  lcd_write_byte(0b01000000);  // cgram address #0
  LCD_RS = 1;

  // pattern is xxxbbbbb

  // arrow right
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000010);
  lcd_write_byte(0b00011111);
  lcd_write_byte(0b00000010);
  lcd_write_byte(0b00000100);

  // arrow left
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00001000);
  lcd_write_byte(0b00011111);
  lcd_write_byte(0b00001000);
  lcd_write_byte(0b00000100);

  // arrow up
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00001110);
  lcd_write_byte(0b00010101);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00001100);
  lcd_write_byte(0b00011000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);

  // node
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00001110);
  lcd_write_byte(0b00010001);
  lcd_write_byte(0b00010001);
  lcd_write_byte(0b00010001);
  lcd_write_byte(0b00001110);

  // marked node
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00001110);
  lcd_write_byte(0b00010001);
  lcd_write_byte(0b00010101);
  lcd_write_byte(0b00010001);
  lcd_write_byte(0b00001110);

  // line
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00011111);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);

  // corner bottom left
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000110);
  lcd_write_byte(0b00000011);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);

  // corner bottom right
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00000100);
  lcd_write_byte(0b00001100);
  lcd_write_byte(0b00011000);
  lcd_write_byte(0b00000000);
  lcd_write_byte(0b00000000);

  lcd_clear_and_home();
}

/* Display a pattern of custom characters from cgram. 
 * Also performs Clear and Home.
 */
void lcd_draw_logo(void)
{
   // 0 = arrow right
   // 1 = arrow left
   // 2 = arrow up
   // 3 = node
   // 4 = marked node
   // 5 = line
   // 6 = corner bottom left
   // 7 = corner bottom right

   lcd_clear_and_home();

   lcd_write_char(0);
   lcd_write_char(3);
   lcd_write_char(5);
   lcd_write_char(5);
   lcd_write_char(5);
   lcd_write_char(0);
   lcd_write_char(3);
   lcd_write_char(0);
   lcd_write_char(3);
   lcd_write_char(5);
   lcd_write_char(5);
   lcd_write_char(0);
   lcd_write_char(3);
   lcd_write_char(5);
   lcd_write_char(5);
   lcd_write_char(3);

   lcd_goto(64);

   lcd_write_char(' ');
   lcd_write_char(6);
   lcd_write_char(5);
   lcd_write_char(0);
   lcd_write_char(3);
   lcd_write_char(5);
   lcd_write_char(2);
   lcd_write_char(' ');
   lcd_write_char(6);
   lcd_write_char(0);
   lcd_write_char(4);
   lcd_write_char(1);
   lcd_write_char(7);
   lcd_write_char(4);
   lcd_write_char(1);
   lcd_write_char(7);
}