【急，在线等！！！！】使用timer 设置PWM问题

用事例代码设置PWM的频率不能设置频率小于700HZ的，应该是定时器设置为16位的原因，怎么样设置32位定时器，可以产生700HZ以下频率的PWM，

static void board_pwm_init()
{
Power_setDependency(PERIPH_GPT1);
TimerConfigure(GPT1_BASE, TIMER_CFG_SPLIT_PAIR|TIMER_CFG_A_PWM|TIMER_CFG_B_CAP_COUNT);
//TimerConfigure(GPT0_BASE, TIMER_CFG_SPLIT_PAIR|TIMER_CFG_A_PWM|TIMER_CFG_B_CAP_COUNT);
}

void board_pwm_audio(unsigned long freq_Hz, uint8 duration)
{
unsigned long PWM_FREQ = freq_Hz;
unsigned long PWM_DIV_FACTOR = 48000000/PWM_FREQ;
unsigned long TIMER_LOADSET = (PWM_DIV_FACTOR-1);
unsigned long TIMER_MATCH;

if(duration > 100)
duration = 100;
TIMER_MATCH = (PWM_DIV_FACTOR*(100-duration)/100-1);
pr_info("freq_Hz=%d duration=%d \n",freq_Hz,duration);
TimerLoadSet(GPT1_BASE,TIMER_A,TIMER_LOADSET);
TimerDisable(GPT1_BASE, TIMER_A);
PINCC26XX_setMux(hAudio_Pins, Board_AUDIO_PWM, IOC_PORT_MCU_PORT_EVENT2);
TimerMatchSet(GPT1_BASE,TIMER_A,TIMER_MATCH);
TimerEnable(GPT1_BASE,TIMER_A);
}