MSP432E401Y: PWM外设的频率问题

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 * Copyright (c) 2015-2019, Texas Instruments Incorporated
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/*
 *  ======== pwmled2.c ========
 */
/* For usleep() */
#include <unistd.h>
#include <stddef.h>

/* Driver Header files */
#include <ti/drivers/PWM.h>

/* Driver configuration */
#include "ti_drivers_config.h"

/*
 *  ======== mainThread ========
 *  Task periodically increments the PWM duty for the on board LED.
 */
void *mainThread(void *arg0)
{
    /* Period and duty in microseconds */
    uint16_t   pwmPeriod = 3000;
    uint16_t   duty = 0;
    uint16_t   dutyInc = 100;

    /* Sleep time in microseconds */
    uint32_t   time = 50000;
    PWM_Handle pwm1 = NULL;
    PWM_Handle pwm2 = NULL;
    PWM_Params params;

    /* Call driver init functions. */
    PWM_init();

    PWM_Params_init(&params);
    params.dutyUnits = PWM_DUTY_US;
    params.dutyValue = 0;
    params.periodUnits = PWM_PERIOD_US;
    params.periodValue = pwmPeriod;
    pwm1 = PWM_open(CONFIG_PWM_0, &params);
    if (pwm1 == NULL) {
        /* CONFIG_PWM_0 did not open */
        while (1);
    }

    PWM_start(pwm1);

    pwm2 = PWM_open(CONFIG_PWM_1, &params);
    if (pwm2 == NULL) {
        /* CONFIG_PWM_0 did not open */
        while (1);
    }

    PWM_start(pwm2);

    /* Loop forever incrementing the PWM duty */
    while (1) {
        PWM_setDuty(pwm1, duty);

        PWM_setDuty(pwm2, duty);

        duty = (duty + dutyInc);

        if (duty == pwmPeriod || (!duty)) {
            dutyInc = - dutyInc;
        }

        usleep(time);
    }
}