#include <xc.h>

// for LCD commands/settings

#define CLEAR_DISPLAY 0x01

#define CURSOR_HOME 0x02

#define FUNCTION_SETTINGS 0x28

#define DISPLAY_SETTINGS 0x0C

#define ENTRY_MODE 0x06

#define SHIFT_CURSOR_RIGHT 0x14

#define SHIFT_CURSOR_LEFT 0x10

#define ROW1 0x80

#define ROW2 0xC0

// for LCD pins

#define RS RB4

#define RS_TRIS TRISB4

#define RW RB5

#define RW_TRIS TRISB5

#define EN RB6

#define EN_TRIS TRISB6

#define D4 RC0

#define D4_TRIS TRISC0

#define D5 RC1

#define D5_TRIS TRISC1

#define D6 RC2

#define D6_TRIS TRISC2

#define D7 RC3

#define D7_TRIS TRISC3

void tmr0_delay(char a);

void lcd_en(char a);

void lcd_port(char a, char b, char c);

void lcd_cmd(char a, char b, char c);

void lcd_set_cursor(char a, char b);

void lcd_init(void);

void lcd_write_char(char a);

void lcd_write_string(char *a);

void tmr0_delay(char a){

TMR0IE = 0;

TMR0IF = 0;

TMR0 = 0x00;

OPTION_REG = a;

while(!TMR0IF);

}

void lcd_en(char a){ //EN is triggered by a falling edge

EN_TRIS = 0;

EN = 1;

tmr0_delay(a);

EN = 0;

tmr0_delay(a);

}

void lcd_port(char a, char b, char c){

// 4-BIT MODE

// "&" is a bit-wise logical operand

// four high bits

if(a & 0x10) D4 = 1; else D4 = 0;

if(a & 0x20) D5 = 1; else D5 = 0;

if(a & 0x40) D6 = 1; else D6 = 0;

if(a & 0x80) D7 = 1; else D7 = 0;

lcd_en(b);

// four low bits

if(a & 0x01) D4 = 1; else D4 = 0;

if(a & 0x02) D5 = 1; else D5 = 0;

if(a & 0x04) D6 = 1; else D6 = 0;

if(a & 0x08) D7 = 1; else D7 = 0;

lcd_en(c);

}

void lcd_cmd(char a, char b, char c){

RS_TRIS = 0;

RS = 0; // command

RW_TRIS = 0;

RW = 0; // write

D4_TRIS = 0;

D5_TRIS = 0;

D6_TRIS = 0;

D7_TRIS = 0;

lcd_port(a,b,c);

}

void lcd_set_cursor(char a, char b){

char temp;

if(a == 1)

{

temp = ROW1 + b;

lcd_cmd(temp, 0x00, 0x00);

}

else if(a == 2)

{

temp = ROW2 + b;

lcd_cmd(temp, 0x00, 0x00);

}

}

void lcd_init(void){

// configure pins - specific to PIC16F1829

ANSELC = 0; // digital

WPUC = 0; // disabled weak pull up

TRISC = 0; // outputs

PORTC = 0;

ANSELB = 0; // digital

WPUB = 0; // disabled weak pull up

TRISB7 = 0; // outputs

PORTB = 0;

// delay for LCD power up

tmr0_delay(0);

//configure lcd

// 4-BIT MODE

RS_TRIS = 0;

RS = 0; // command

RW_TRIS = 0;

RW = 0; // write

D7 = 0;

D6 = 0;

D5 = 1;

D4 = 0;

lcd_en(0);

// standard configuration

lcd_cmd(FUNCTION_SETTINGS, 0x00, 0x00);

lcd_cmd(CLEAR_DISPLAY, 0x00, 0x00);

lcd_cmd(DISPLAY_SETTINGS, 0x00, 0x00);

lcd_cmd(CURSOR_HOME, 0x00, 0x00);

}

void lcd_write_char(char a){

RS_TRIS = 0;

RS = 1; // data

RW_TRIS = 0;

RW = 0; // write

D4_TRIS = 0;

D5_TRIS = 0;

D6_TRIS = 0;

D7_TRIS = 0;

lcd_port(a, 0x00, 0x00);

}

void lcd_write_string(char *a){

int i;

for(i=0;a[i]!='\0';i++)

lcd_write_char(a[i]);

}