/*P12_1.c: Programming PCD8544 GLCD via SPI with FRDM-KL25Z 

 * PTD1 pin as SPI SCK 
 * PTD2 pin as SPI MOSI
 * PTC8 reset pin
 * PTD0 register select pin
 * PTC9 chip select
 */ 
 
#include "MKL25Z4.h"

#define RESET 0x0100    /* PTC8 reset pin */
#define DC    0x0001    /* PTD0 register select pin */
#define CE    0x0200    /* PTC9 chip select */

/* define the pixel size of display */
#define GLCD_WIDTH  84
#define GLCD_HEIGHT 48

void GLCD_setCursor(unsigned char x, unsigned char y);
void GLCD_clear(void);
void GLCD_init(void);
void GLCD_data_write(unsigned char data); 
void GLCD_command_write(unsigned char data);
void SPI0_init(void);
void SPI0_write(unsigned char data);
void GLCD_putchar(int c);

/* sample font table */
const char font_table[][6] = {
    {0x7e, 0x11, 0x11, 0x11, 0x7e, 0},  /* A */
    {0x7f, 0x49, 0x49, 0x49, 0x36, 0},  /* B */
    {0x3e, 0x41, 0x41, 0x41, 0x22, 0}}; /* C */
    
int main(void) {
    GLCD_init();    /* initialize the GLCD controller */
    GLCD_clear();   /* clear display and home the cursor */

    GLCD_putchar(0);    /* display letter A */
    GLCD_putchar(1);    /* display letter B */
    GLCD_putchar(2);    /* display letter C */
    
    while(1) { }
}

void GLCD_putchar(int c) {
    int i;
    for (i = 0; i < 6; i++)
        GLCD_data_write(font_table[c][i]);
}

void GLCD_setCursor(unsigned char x, unsigned char y) {
    GLCD_command_write(0x80 | x);  /* column */
    GLCD_command_write(0x40 | y);  /* bank (8 rows per bank) */
}

/* clears the GLCD by writing zeros to the entire screen */
void GLCD_clear(void) {
    int32_t index;
    for (index = 0 ; index < (GLCD_WIDTH * GLCD_HEIGHT / 8) ; index++)
        GLCD_data_write(0x00);
    
    GLCD_setCursor(0, 0); /*After we clear the display, return to the home position */
}

void SPI0_init(void) {
    SIM->SCGC5 |= 0x1000;       /* enable clock to Port D */
    SIM->SCGC5 |= 0x0800;       /* enable clock to Port C */
    PORTD->PCR[1] = 0x200;      /* make PTD1 pin as SPI SCK */
    PORTD->PCR[2] = 0x200;      /* make PTD2 pin as SPI MOSI */
    PORTD->PCR[0] = 0x100;      /* make PTD0 pin as DC */
    PORTC->PCR[8] = 0x100;      /* make PTC8 pin as RST */
    PORTC->PCR[9] = 0x100;      /* make PTC9 pin as CE */
    PTD->PDDR |= 0x01;          /* make PTD0 as output pin for DC */
    PTC->PDDR |= 0x0200;        /* make PTC9 as output pin for /CE */
    PTC->PSOR = CE;             /* deassert /CE */
    PTC->PDDR |= 0x0100;        /* make PTC8 as output pin for RESET */
    PTC->PCOR = RESET;          /* assert reset */
    
    SIM->SCGC4 |= 0x400000;     /* enable clock to SPI0 */
    SPI0->C1 = 0x10;            /* disable SPI and make SPI0 master */
    SPI0->BR = 0x60;            /* set Baud rate to 1 MHz */
    SPI0->C1 |= 0x40;           /* Enable SPI module */
}

/* send the initialization commands to PCD8544 GLCD controller */
void GLCD_init(void) {
    SPI0_init();

    /* hardware reset of GLCD controller */
    PTC->PSOR = RESET;          /* deassert reset */

    GLCD_command_write(0x21);   /* set extended command mode */
    GLCD_command_write(0xB0);   /* set LCD Vop for contrast */
    GLCD_command_write(0x04);   /* set temp coefficient */
    GLCD_command_write(0x14);   /* set LCD bias mode 1:48 */
    GLCD_command_write(0x20);   /* set normal command mode */
    GLCD_command_write(0x0C);   /* set display normal mode */
}

/* write to GLCD controller data register */
void GLCD_data_write(unsigned char data) {
    /* select data register */
    PTD->PSOR = DC;             /* set DC */
    /* send data via SSI */
    SPI0_write(data);
}

/* write to GLCD controller command register */
void GLCD_command_write(unsigned char data) {
    /* select command register */
    PTD->PCOR = DC;             /* clear DC */
    /* send data via SSI */
    SPI0_write(data);
}

void SPI0_write(unsigned char data) {
    volatile char dummy;
    
    PTC->PCOR = CE;                 /* assert /CE */

    while(!(SPI0->S & 0x20)) { }    /* wait until tx ready */
    SPI0->D = data;                 /* send register address */
    while(!(SPI0->S & 0x80)) { }    /* wait until tx complete */
    dummy = SPI0->D;                /* clear SPRF */
    
    PTC->PSOR = CE;                 /* deasssert /CE */
}