使用keil进行软件仿真时怎样进入外部中断？

现在我可以进入主函数等进行单步仿真等操作，但是不知道应该怎么进入外部中断的函数，请大神指点~

主函数：

#include "stm32f4xx.h"
#include "led.h"
#include "bit_operation.h"
#include "Systick.h"
#include "beep.h"
#include "key.h"
#include "exti.h"

int main()
{
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    My_EXTI_Init();
    BEEP_Init();
    KEY_Init();
    SysTick_Init(168);  //系统时钟为168M
    RCC_HSE_Config(8,336,2,7);
    LED_Init();
    while(1)
    { 
     delay_nms(100);
   led1=!led1;
    }
}

这是我进行的外部中断的设置：

    NVIC_InitTypeDef NVIC_InitStruct;
     EXTI_InitTypeDef EXTI_InitStruct;

     RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG,ENABLE);

     SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA,EXTI_PinSource0);

     NVIC_InitStruct.NVIC_IRQChannel=EXTI0_IRQn;
     NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority=2;
     NVIC_InitStruct.NVIC_IRQChannelSubPriority=2;
     NVIC_InitStruct.NVIC_IRQChannelCmd=ENABLE;
     NVIC_Init(&NVIC_InitStruct);

     EXTI_InitStruct.EXTI_Line=EXTI_Line0;
     EXTI_InitStruct.EXTI_Mode=EXTI_Mode_Interrupt;
     EXTI_InitStruct.EXTI_Trigger=EXTI_Trigger_Rising;
     EXTI_InitStruct.EXTI_LineCmd=ENABLE;
     EXTI_Init(&EXTI_InitStruct);

最后是对应的中断服务函数：

void EXTI0_IRQHandler(void)
{
    if(EXTI_GetITStatus(EXTI_Line0)==1)
    {
        delay_nms(10);
        if(KEY_UP==1)
        {
            led2=0;
        }
    }
    EXTI_ClearITPendingBit(EXTI_Line0);
}

https://www.csdn.net/gather_2a/MtjaQg5sOTg2NTUtYmxvZwO0O0OO0O0O.html