/* www.MicroDigitalEd.com
 * p11_2.c Variable duty cycle PWM to control LED intensity
 *
 * This program uses Timer_A0.4 to generate PWM output at 60 Hz
 * and variable duty cycle.
 * The program is based on p11_1.c with two changes.
 * 1. In the infinite loop, the duty cycle is increased by 5%
 *    every 50ms. When it reaches 100%, it wraps around.
 * 2. The timer output is available on P2.7 and is also mapped to
 *    P2.1 (Green LED).
 *
 * Tested with Keil 5.20 and MSP432 Device Family Pack V2.2.0
 * on XMS432P401R Rev C.
 */

#include "msp.h"

void delayMs(int n);
void portRemap(void);

int main(void) {
	/* Configure P2.7 as Timer A0.4 output */
    P2->SEL0 |= 0x80;
    P2->SEL1 &= ~0x80;
    P2->DIR |= 0x80;

    portRemap();                    /* remap output to P2.1 green LED */

    /* configure TimerA0.4 as PWM */
    TIMER_A0->CCR[0] = 50000-1;     /* PWM Period */
    TIMER_A0->CCR[4] = 500;         /* begin from 1% */
    TIMER_A0->CCTL[4] = 0xE0;       /* CCR4 reset/set mode */
    TIMER_A0->CTL = 0x0214;         /* use SMCLK, count up, clear TA0R register */

    while (1) {
        /* increase duty cycle by 5% */
        TIMER_A0->CCR[4] += 2500;
        if (TIMER_A0->CCR[4] > 50000)   /* wrap around when reaches 100% */
            TIMER_A0->CCR[4] = 500;	/* begin from 1% */
        delayMs(50);
    }
}

void portRemap(void) {
    PMAP->KEYID = 0x2D52;           /* unlock PMAP */

    P2MAP->PMAP_REGISTER1 = 23;     /* remap P2.1 to 23 (TPM0.4) */
    P2->DIR |= 2;
    P2->SEL0 |= 2;
    P2->SEL1 &= ~2;

    PMAP->CTL = 1;                  /* lock PMAP */
    PMAP->KEYID = 0;
}

/* delay milliseconds when system clock is at 3 MHz */
void delayMs(int n) {
    int i, j;
    
    for (j = 0; j < n; j++)
        for (i = 750; i > 0; i--);      /* Delay */
}