/* p10_1: Relay control
 * This program turns the relay connected to P4.0 on and off every second.
 *
 * Tested with Keil 5.20 and MSP432 Device Family Pack V2.2.0
 * on XMS432P401R Rev C.
 */
#include "msp.h"

void delayMs(int n);

int main(void) {
    P4->SEL1 &= ~1;           /* configure P4.0 as simple I/O */
    P4->SEL0 &= ~1;
    P4->DIR |= 1;             /* P4.0 set as output pin */

    while (1) {
        P4->OUT |= 1;         /* turn on P4.0 */
        delayMs(1000);
        P4->OUT &= ~1;        /* turn off P4.0 */
        delayMs(1000);
    }
}

/* 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 1 ms */
}