TMS320F28375S: Ecap只能进入一次中断

我用信号发生器生成一个方波，输入到Ecap的引脚，设置触发源为EVENT_4，补货为连续捕获模式，但是不知道为什么只能进入一次中断，麻烦帮忙看看是哪里有问题

这是初始化的代码

void initECAP()
{
    //
    // Disable ,clear all capture flags and interrupts
    //
    ECAP_disableInterrupt(ECAP1_BASE,
                          (ECAP_ISR_SOURCE_CAPTURE_EVENT_1  |
                           ECAP_ISR_SOURCE_CAPTURE_EVENT_2  |
                           ECAP_ISR_SOURCE_CAPTURE_EVENT_3  |
                           ECAP_ISR_SOURCE_CAPTURE_EVENT_4  |
                           ECAP_ISR_SOURCE_COUNTER_OVERFLOW |
                           ECAP_ISR_SOURCE_COUNTER_PERIOD   |
                           ECAP_ISR_SOURCE_COUNTER_COMPARE));
    ECAP_clearInterrupt(ECAP1_BASE,
                        (ECAP_ISR_SOURCE_CAPTURE_EVENT_1  |
                         ECAP_ISR_SOURCE_CAPTURE_EVENT_2  |
                         ECAP_ISR_SOURCE_CAPTURE_EVENT_3  |
                         ECAP_ISR_SOURCE_CAPTURE_EVENT_4  |
                         ECAP_ISR_SOURCE_COUNTER_OVERFLOW |
                         ECAP_ISR_SOURCE_COUNTER_PERIOD   |
                         ECAP_ISR_SOURCE_COUNTER_COMPARE));

    //
    // Disable CAP1-CAP4 register loads
    //
    ECAP_disableTimeStampCapture(ECAP1_BASE);

    //
    // Configure eCAP
    //    Enable capture mode.
    //    One shot mode, stop capture at event 4.
    //    Set polarity of the events to rising, falling, rising, falling edge.
    //    Set capture in time difference mode.
    //    Select input from XBAR7.
    //    Enable eCAP module.
    //    Enable interrupt.
    //
    ECAP_stopCounter(ECAP1_BASE);
    ECAP_enableCaptureMode(ECAP1_BASE);

    ECAP_setCaptureMode(ECAP1_BASE, ECAP_CONTINUOUS_CAPTURE_MODE, ECAP_EVENT_4);

    ECAP_setEventPolarity(ECAP1_BASE, ECAP_EVENT_1, ECAP_EVNT_FALLING_EDGE);
    ECAP_setEventPolarity(ECAP1_BASE, ECAP_EVENT_2, ECAP_EVNT_FALLING_EDGE);
    ECAP_setEventPolarity(ECAP1_BASE, ECAP_EVENT_3, ECAP_EVNT_FALLING_EDGE);
    ECAP_setEventPolarity(ECAP1_BASE, ECAP_EVENT_4, ECAP_EVNT_FALLING_EDGE);

    ECAP_enableCounterResetOnEvent(ECAP1_BASE, ECAP_EVENT_1);
    ECAP_enableCounterResetOnEvent(ECAP1_BASE, ECAP_EVENT_2);
    ECAP_enableCounterResetOnEvent(ECAP1_BASE, ECAP_EVENT_3);
    ECAP_enableCounterResetOnEvent(ECAP1_BASE, ECAP_EVENT_4);

    XBAR_setInputPin(XBAR_INPUT7, 19);

    ECAP_enableLoadCounter(ECAP1_BASE);
    ECAP_setSyncOutMode(ECAP1_BASE, ECAP_SYNC_OUT_DISABLED);
    ECAP_startCounter(ECAP1_BASE);
    ECAP_enableTimeStampCapture(ECAP1_BASE);
    ECAP_reArm(ECAP1_BASE);

    ECAP_enableInterrupt(ECAP1_BASE, ECAP_ISR_SOURCE_CAPTURE_EVENT_4);
}

这是中断的代码

__interrupt void ecap1ISR(void)
{
    //
    // Get the capture counts. Each capture should be 4x the ePWM count
    // because of the ePWM clock dividers.
    //
    cap1Count = ECAP_getEventTimeStamp(ECAP1_BASE, ECAP_EVENT_1);
    cap2Count = ECAP_getEventTimeStamp(ECAP1_BASE, ECAP_EVENT_2);
    cap3Count = ECAP_getEventTimeStamp(ECAP1_BASE, ECAP_EVENT_3);
    cap4Count = ECAP_getEventTimeStamp(ECAP1_BASE, ECAP_EVENT_4);

    calc_pulse1 = cap4Count - cap1Count;
    calc_time = calc_pulse1 * 5.1282051282 * 10e-9;
    rpm = 1/calc_time*20;
    ECAP_clearInterrupt(ECAP1_BASE,ECAP_ISR_SOURCE_CAPTURE_EVENT_4);
    ECAP_clearGlobalInterrupt(ECAP1_BASE);

    // Start eCAP
    //
    ECAP_reArm(ECAP1_BASE);

    //
    // Acknowledge the group interrupt for more interrupts.
    //
    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP4);

}