Timer_A 定时中断问题

Timer_A_initUpModeParam param = {0};
param.clockSource = TIMER_A_CLOCKSOURCE_ACLK;
param.clockSourceDivider = TIMER_A_CLOCKSOURCE_DIVIDER_1;
param.timerPeriod = 328;
param.timerInterruptEnable_TAIE = TIMER_A_TAIE_INTERRUPT_DISABLE;
param.captureCompareInterruptEnable_CCR0_CCIE = TIMER_A_CCIE_CCR0_INTERRUPT_ENABLE;
param.timerClear = TIMER_A_DO_CLEAR;
param.startTimer = true;
Timer_A_initUpMode(TIMER_A0_BASE, &param);

Timer_A初始化程序如上所示，在中断函数中反转某个I/O，用示波器观察，方波的频率和占空比都在变化，这是为什么？如果将param.timerPeriod 的值增大，例如param.timerPeriod = 3277，则得到的方波频率和占空比都不会变化，param.timerPeriod是写入TAxCCR0寄存器，应该没有最小限制值得说法吧，ACLK=32768Hz