/*
 * Simple program to demonstrate the use of OLED on Digilent Orbit BoosterPack
 * The OLED uses Solomon Systech SSD1306 controller.
 * The controller is configured so that the origin (0, 0) is at the upper left corner.
 * The display is not cleared in initialization.
 */

#include "TM4C123GH6PM.h"

void OrbitOled_init(void);
void SSI3Write(unsigned char data);
void delayMs(int n);

int main(void) {
    int i, j;

    char font_table[][6] = {    /* sample font table */
        {0x7e, 0x11, 0x11, 0x11, 0x7e, 0},  /* A */
        {0x7f, 0x49, 0x49, 0x49, 0x36, 0},  /* B */
        {0x3e, 0x41, 0x41, 0x41, 0x22, 0}}; /* C */

    OrbitOled_init();

    /* write ABC at the beginning of first line */
    for (j = 0; j < 3; j++)
        for (i = 0; i < 6; i++)
            SSI3Write(font_table[j][i]);

    /* clear the rest of the line */
    for (i = 0; i < 110; i++)
        SSI3Write(0);

    for (;;) {  /* infinite loop */
    }
}

void OrbitOled_init(void) {
	/* Initialize SSI3 */
    SYSCTL->RCGCSSI |= 8;       /* enable clock to SSI3 */
    SYSCTL->RCGCGPIO |= 8;      /* enable clock to GPIOD for SSI3 */
    SYSCTL->RCGCGPIO |= 0x20;   /* enable clock to GPIOF */
    SYSCTL->RCGCGPIO |= 0x10;   /* enable clock to GPIOE */

    /* configure SSI3 as SPI for OLED */
    SSI3->CR1 = 0;              /* disable SSI and make it master */
    SSI3->CC = 0;               /* use system clock */
    SSI3->CPSR = 2;             /* prescaler divided by 2 */
    SSI3->CR0 = 0x0007;         /* 8 MHz SSI clock, SPI mode, 8 bit data */
    SSI3->CR1 |= 2;             /* enable SSI1 */

    /* configure PORTD 3, 0 for SSI3 clock and Tx */
    GPIOD->AMSEL &= ~0x09;      /* disable analog for these pins */
    GPIOD->DEN |= 0x09;         /* and make them digital */
    GPIOD->AFSEL |= 0x09;       /* enable alternate function */
    GPIOD->PCTL &= ~0x0000F00F; /* assign pins to SSI3 */
    GPIOD->PCTL |= 0x00001001;  /* assign pins to SSI3 */

    /* configure the rest of the control pins */
    /* VBAT (PF1) */
    GPIOF->DIR |= 0x02;         /* set PF1 as output pin */
    GPIOF->DEN |= 0x02;         /* set PF1 as digital pin */
    GPIOF->DATA |= 0x02;        /* set PF1 high */

    /* VDD (PE1) */
    GPIOE->DIR |= 0x02;         /* set PE1 as output pin */
    GPIOE->DEN |= 0x02;         /* set PE1 as digital pin */
    GPIOE->DATA |= 0x02;        /* set PE1 high */

    /* DC (PD7 needs be unlocked to modify) */
    GPIOD->LOCK = 0x4C4F434B;   /* unlock commit register */
    GPIOD->CR = 0x80;           /* make PD7 configurable */
    GPIOD->LOCK = 0;            /* lock commit register */
    GPIOD->DIR |= 0x80;         /* set PD7 pin as output pin */
    GPIOD->DEN |= 0x80;         /* set PD7 pin as digital pin */
    GPIOD->DATA |= 0x80;        /* set PD7 high */

    /* RES (PE5) */
    GPIOE->DIR |= 0x20;         /* set PE5 pin as output pin */
    GPIOE->DEN |= 0x20;         /* set PE5 pin as digital pin */
    GPIOE->DATA |= 0x20;        /* set PE5 high */

    /* CS (PD1) */
    GPIOD->DIR |= 0x02;         /* set PD1 pin as output pin */
    GPIOD->DEN |= 0x02;         /* set PD1 pin as digital pin */
    GPIOD->DATA |= 0x02;        /* set PD1 high */

    /* start OLED initialization sequence */
    GPIOD->DATA &= ~0x80;       /* clear DC bit to go into command mode */

    GPIOE->DATA &= ~0x02;       /* turn on Vdd */
	delayMs(1);                 /* wait for power up */

    SSI3Write(0xAE);            /* turn display off during initialization */

    GPIOE->DATA &= ~0x20;	    /* pulse reset */
	delayMs(1);
    GPIOE->DATA |= 0x20;

    SSI3Write(0x8D);            /* enable charge pump */
    SSI3Write(0x14);
    SSI3Write(0xD9);            /* set pre-charge period */
    SSI3Write(0xF1);

    GPIOF->DATA &= ~0x02;	    /* turn on Vcc */
	delayMs(100);

    SSI3Write(0xA1);			/* remap columns */
    SSI3Write(0xC8);			/* remap rows */

    SSI3Write(0xDA);			/* set COM config */
    SSI3Write(0x20);			/* scan top to bottom */

    SSI3Write(0xAF);	        /* turn on display */

    /* set cursor to the upper left corner */
    SSI3Write(0x22);		    /* set page */
    SSI3Write(0);		        /* to page 0 */

    SSI3Write(0x00);		    /* set low nibble of column */
    SSI3Write(0x10);		    /* set high nibble of column */

    GPIOD->DATA |= 0x80;        /* exit command mode */
}

void SSI3Write(unsigned char data)
{
    GPIOD->DATA &= ~0x02;       /* assert SS low */
    while((SSI3->SR & 2) == 0); /* wait until FIFO not full */
    SSI3->DR = data;            /* transmit high byte */
    while(SSI3->SR & 0x10);     /* wait until transmit complete */
    GPIOD->DATA |= 0x02;        /* keep SS idle high */
}

/* delay n milliseconds (16 MHz CPU clock) */
void delayMs(int n) {
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3180; j++)
            {}  /* do nothing for 1 ms */
}

/* This function is called by the startup assembly
 * code to perform system specific initialization tasks. */
void SystemInit(void) {
    /* Grant coprocessor access
       This is required since TM4C123G has
       a floating point coprocessor */
    SCB->CPACR |= 0x00f00000;
}