/**********************************************************************
 * LCD display driver for SC1602 module (HITACHI HD44780U controller)
 * 4 bit transfer mode
 *
 * connection:
 * bit0		LCD E
 * bit1		LCD RS
 * bit2:3	N/C
 * bit4:7	LCD Data
 **********************************************************************/

#include <htc.h>
#include "lcd4.h"

/* configure following definition */
#define _XTAL_FREQ 10000000
#define LCD_PORT PORTB		/* set LCD port */
#define LCD_CONFIGREG TRISB	/* configuration register */
#define LCD_E RB0		/* set E bit of I/O port */
#define LCD_RS RB1		/* set RS bit of I/O port */

#ifndef _XTAL_FREQ
  #error _XTAL_FREQ is not defined
#endif

#if _XTAL_FREQ > 18000000	/* if clock is faster than 18MHz */
  #define STROBE (LCD_E=1,asm("nop"),LCD_E=0)
#else
  #define STROBE (LCD_E=1,LCD_E=0)
#endif

/*
 LCD initialization
*/
void Init_LCD4(void){
    LCD_CONFIGREG=0b00001100;
    __delay_ms(15);
    LCD_PORT=0x30;	/* E=0, RS=0, command=0x30 */
    STROBE;
    __delay_ms(5); /* > 4.1ms */
    STROBE;
    __delay_us(128); /* >100us */
    STROBE;
    /* set 4bit mode */
    LCD_PORT=0x20; /* E=0, RS=0, command=0x20 */
    STROBE;
    Putc_LCD4(0x28, LCD_CMD);	/* display mode */
    Putc_LCD4(0x0C, LCD_CMD);	/* display on */
    Clr_LCD4;
    Putc_LCD4(0x06, LCD_CMD);	/* entry mode */
}

/*
 write one byte character or command
 c: ASCII code or command
 rs: LCD_CMD or LCD_DATA
*/
void Putc_LCD4(char c, char rs){
    __delay_us(52); /* >40us */
    LCD_RS=rs;
    rs=LCD_PORT & 0x0f;
    LCD_PORT=((c & 0xf0)+rs);	/* E=0, RS=rs, high addr */
    STROBE;
    LCD_PORT=((c << 4)+rs);	/* E=0, RS=rs, low addr */
    STROBE;
}

/*
 write character string
 ptr: start pointer of character string which is NULL terminated.
*/
void Puts_LCD4(char *ptr){
    while(*ptr){
        Putc_LCD4(*ptr++, LCD_DATA);
    }
}

/*
 shift display to left n times
*/
void Shift_LN(int n){
    int i;
    for (i=0;i<n;i++){
        Shift_L;
    }
}

/*
 shift display to right n times
*/
void Shift_RN(int n){
    int i;
    for (i=0;i<n;i++){
        Shift_R;
    }
}

/*
 CGRAM write
*/
void CGRAM(char c, char *rom_addr){
    int i;
    Putc_LCD4(0b01000000+(c << 3), LCD_CMD);
    for(i=0; i<8; i++){
        Putc_LCD4(EEPROM_READ(rom_addr+i), LCD_DATA);
    }
}