/* p3_1.c: Initialize and display "Hello" on the LCD using 8-bit data mode.

 * Data pins use Port D, control pins use Port A.
 * This program does not poll the status of the LCD.  
 * It uses delay to wait out the time LCD controller is busy.
 * Timing is more relax than the HD44780 datasheet to accommodate the
 * variations among the LCD modules.
 * You may want to adjust the amount of delay for your LCD controller. 
 */

#include <MKL25Z4.H>

#define RS 0x04     /* PTA2 mask */ 
#define RW 0x10     /* PTA4 mask */ 
#define EN 0x20     /* PTA5 mask */

void delayMs(int n);
void LCD_command(unsigned char command);
void LCD_data(unsigned char data);
void LCD_init(void);

int main(void)
{
    LCD_init();
    for(;;)
    {
        LCD_command(1);         /* clear display */
        delayMs(500);
        LCD_command(0x80);      /* set cursor at first line */
        LCD_data('H');          /* write the word */
        LCD_data('e');
        LCD_data('l');
        LCD_data('l');
        LCD_data('o');
        delayMs(500);
    }
}

void LCD_init(void)
{
    SIM->SCGC5 |= 0x1000;       /* enable clock to Port D */ 
    PORTD->PCR[0] = 0x100;      /* make PTD0 pin as GPIO */
    PORTD->PCR[1] = 0x100;      /* make PTD1 pin as GPIO */
    PORTD->PCR[2] = 0x100;      /* make PTD2 pin as GPIO */
    PORTD->PCR[3] = 0x100;      /* make PTD3 pin as GPIO */
    PORTD->PCR[4] = 0x100;      /* make PTD4 pin as GPIO */
    PORTD->PCR[5] = 0x100;      /* make PTD5 pin as GPIO */
    PORTD->PCR[6] = 0x100;      /* make PTD6 pin as GPIO */
    PORTD->PCR[7] = 0x100;      /* make PTD7 pin as GPIO */
    PTD->PDDR = 0xFF;           /* make PTD7-0 as output pins */
    
    SIM->SCGC5 |= 0x0200;       /* enable clock to Port A */ 
    PORTA->PCR[2] = 0x100;      /* make PTA2 pin as GPIO */
    PORTA->PCR[4] = 0x100;      /* make PTA4 pin as GPIO */
    PORTA->PCR[5] = 0x100;      /* make PTA5 pin as GPIO */
    PTA->PDDR |= 0x34;          /* make PTA5, 4, 2 as output pins */

    delayMs(30);                /* initialization sequence */
    LCD_command(0x30);
    delayMs(10);
    LCD_command(0x30);
    delayMs(1);
    LCD_command(0x30);
    
    LCD_command(0x38);      /* set 8-bit data, 2-line, 5x7 font */
    LCD_command(0x06);      /* move cursor right */
    LCD_command(0x01);      /* clear screen, move cursor to home */
    LCD_command(0x0F);      /* turn on display, cursor blinking */
}

void LCD_command(unsigned char command)
{
    PTA->PCOR = RS | RW;    /* RS = 0, R/W = 0 */
    PTD->PDOR = command;
    PTA->PSOR = EN;         /* pulse E */
    delayMs(0);
    PTA->PCOR = EN;
    if (command < 4)
        delayMs(4);         /* command 1 and 2 needs up to 1.64ms */
    else
        delayMs(1);         /* all others 40 us */
}

void LCD_data(unsigned char data)
{
    PTA->PSOR = RS;         /* RS = 1, R/W = 0 */
    PTA->PCOR = RW;
    PTD->PDOR = data;
    PTA->PSOR = EN;         /* pulse E */
    delayMs(0);
    PTA->PCOR = EN;
    delayMs(1);
}

/* Delay n milliseconds
 * The CPU core clock is set to MCGFLLCLK at 41.94 MHz in SystemInit().
 */
void delayMs(int n) {
    int i;
    int j;
    for(i = 0 ; i < n; i++)
        for(j = 0 ; j < 7000; j++) { }
}