/*
 * GccApplication2.c
 *
 * Created: 4/10/2017 4:07:00 PM
 *  Author: Derrick
 */ 
#define	F_CPU 20000000UL

#include <avr/io.h>
#include <util/delay.h>
#include <avr/pgmspace.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set

#define LCD_port PORTA
#define LCD_direction DDRA
#define DB7 (1 << PA0)
#define DB6 (1 << PA1)
#define DB5 (1 << PA2)
#define DB4 (1 << PA3)
#define E (1 << PA4)
#define RS (1 << PA5)

#define long_delay() _delay_ms(1000) // delay before redraw
#define lcd_delay() _delay_ms(10) // delay between commands
#define strobe_delay() _delay_us(1) // delay for strobe

//
// lcd_putchar
//    put character in lcdbyte
//
void lcd_putchar(char lcdbyte) {
	//
	// set RS for data
	//
	set(LCD_port, RS);
	//
	// output high nibble
	//
	if bit_test(lcdbyte, 7)
	set(LCD_port, DB7);
	else
	clear(LCD_port, DB7);
	if bit_test(lcdbyte, 6)
	set(LCD_port, DB6);
	else
	clear(LCD_port, DB6);
	if bit_test(lcdbyte, 5)
	set(LCD_port, DB5);
	else
	clear(LCD_port, DB5);
	if bit_test(lcdbyte, 4)
	set(LCD_port, DB4);
	else
	clear(LCD_port, DB4);
	//
	// strobe E
	//
	strobe_delay();
	set(LCD_port, E);
	strobe_delay();
	clear(LCD_port, E);
	//
	// wait
	//
	lcd_delay();
	//
	// output low nibble
	//
	if bit_test(lcdbyte, 3)
	set(LCD_port, DB7);
	else
	clear(LCD_port, DB7);
	if bit_test(lcdbyte, 2)
	set(LCD_port, DB6);
	else
	clear(LCD_port, DB6);
	if bit_test(lcdbyte, 1)
	set(LCD_port, DB5);
	else
	clear(LCD_port, DB5);
	if bit_test(lcdbyte, 0)
	set(LCD_port, DB4);
	else
	clear(LCD_port, DB4);
	//
	// strobe E
	//
	strobe_delay();
	set(LCD_port, E);
	strobe_delay();
	clear(LCD_port, E);
	//
	// wait and return
	//
	lcd_delay();
}
//
// lcd_putcmd
//    put command in lcdbyte
//
void lcd_putcmd(char lcdbyte) {
	//
	// clear RS for command
	//
	clear(LCD_port, RS);
	//
	// output command bits
	//
	PORTA = lcdbyte;
	//
	// strobe E
	//
	strobe_delay();
	set(LCD_port, E);
	strobe_delay();
	clear(LCD_port, E);
	//
	// wait and return
	//
	lcd_delay();
}
//
// lcd_putstring
//    put a null-terminated string in flash
//
void lcd_putstring(PGM_P message) {
	static uint8_t index;
	static char chr;
	index = 0;
	while (1) {
		chr = pgm_read_byte(&(message[index]));
		if (chr == 0)
		return;
		lcd_putchar(chr);
		++index;
	}
}
//
// lcd_init
//    initialize the LCD
//
void lcd_init() {
	//
	// power-up delay
	//
	lcd_delay();
	//
	// initialization sequence
	//
	lcd_putcmd(DB5+DB4);
	lcd_putcmd(DB5+DB4);
	lcd_putcmd(DB5+DB4);
	//
	// 4-bit interface
	//
	lcd_putcmd(DB5);
	//
	// two lines, 5x7 font
	//
	lcd_putcmd(DB5);
	lcd_putcmd(DB7);
	//
	// display on
	//
	lcd_putcmd(0);
	lcd_putcmd(DB7+DB6+DB5);
	//
	// entry mode
	//
	lcd_putcmd(0);
	lcd_putcmd(DB6+DB5);
}

int main(void)
{
    //
    // main
    //
    // set clock divider to /1
    //
    CLKPR = (1 << CLKPCE);
    CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
    //
    // initialize LCD pins
    //
    clear(LCD_port, DB7);
    output(LCD_direction, DB7);
    clear(LCD_port, DB6);
    output(LCD_direction, DB6);
    clear(LCD_port, DB5);
    output(LCD_direction, DB5);
    clear(LCD_port, DB4);
    output(LCD_direction, DB4);
    clear(LCD_port, E);
    output(LCD_direction, E);
    clear(LCD_port, RS);
    output(LCD_direction, RS);
    //
    // initialize LCD
    //
    lcd_init();
    // 
	
	
    // main loop
    //
	
	while(1)
    {
        
        //
        // go to zero position
        //
        lcd_putcmd(0);
        lcd_putcmd(DB5);
        //
        // print first line from flash
        //
        static const char line1[] PROGMEM = "Hello to";
        lcd_putstring((PGM_P) line1);
        //
        // move to second line
        //
        lcd_putcmd(DB7+DB6);
        lcd_putcmd(0);
        //
        // print second line from flash
        //
        static const char line2[] PROGMEM = "you Derrick";
        lcd_putstring((PGM_P) line2);
        //
        // pause
        //
        long_delay();
        //
        // clear display
        //
        lcd_putcmd(0);
        lcd_putcmd(DB4); 
    }
}