/* p5_4.c: This program demonstrates the use of TimerA of Timer0 block to do a delay of the multiple of milliseconds. Because 16-bit mode is used, it will only work up to 4 ms. */


#include "TM4C123GH6PM.h"

void timer0A_delayMs(int ttime);
void delayMs(int n);

int main (void)
{
    /* enable clock to GPIOF at clock gating control register */
    SYSCTL->RCGCGPIO |= 0x20;
    /* enable the GPIO pins for the LED (PF3, 2 1) as output */
    GPIOF->DIR = 0x0E;
    /* enable the GPIO pins for digital function */
    GPIOF->DEN = 0x0E;
    
    while(1)
    {
        GPIOF->DATA = 2;        /* turn on red LED */
        timer0A_delayMs(2);     /* Timer A msec delay */
        GPIOF->DATA = 0;        /* turn off red LED */
        delayMs(3);             /* use old delay function */
    }
}

/* millisecond delay using one-shot mode */
void timer0A_delayMs(int ttime)
{
    SYSCTL->RCGCTIMER |= 1;     /* enable clock to Timer Block 0 */
    TIMER0->CTL = 0;            /* disable Timer before initialization */
    TIMER0->CFG = 0x04;         /* 16-bit option */
    TIMER0->TAMR = 0x01;        /* one-shot mode and down-counter */
    TIMER0->TAILR = 16000 * ttime - 1;  /* Timer A interval load value register*/
    TIMER0->ICR = 0x1;          /* clear the TimerA timeout flag*/
    TIMER0->CTL |= 0x01;        /* enable Timer A after initialization*/
    while ((TIMER0->RIS & 0x1) == 0) ;  /* wait for TimerA timeout flag to set*/
}

/* 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;
}