STM32基本定时器中断

学习正点原子Mini板，进行到定时器内容时，卡主了好久，自己没头绪找不出哪里出问题了，特此发帖望有技之人指导一下。
程序描述：通过基本定时器7定时500ms吃产生中断，使led翻转。
#include "led.h"
#include "delay.h"
#include "sys.h"
#include "tim1.h"

int main (void)
{
delay_init();//3õê¼»ˉÑóê±oˉêy
NVIC_PriorityGroupConfig( NVIC_PriorityGroup_2);//éèÖÃÖD¶ÏóÅÏ輶·Ö×é
LED_Init();//3õê¼»ˉledoˉêy       
TIM7_Init(4999,7199);
while(1);
}



#include "tim1.h"
#include "led.h"
void TIM7_Init(u16 arr,u16 psc)
{
        TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
        NVIC_InitTypeDef NVIC_InitStruct;
       
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM7,ENABLE);
               
//定时器中断配置
        TIM_TimeBaseInitStruct.TIM_Period=arr;
        TIM_TimeBaseInitStruct.TIM_Prescaler=psc;//Ô¤·ÖÆμÏμêy
        TIM_TimeBaseInitStruct.TIM_CounterMode=TIM_CounterMode_Up;
        TIM_TimeBaseInitStruct.TIM_ClockDivision=TIM_CKD_DIV1;
        TIM_TimeBaseInit(TIM1,&TIM_TimeBaseInitStruct);

        TIM_ITConfig(TIM7,TIM_IT_Update,ENABLE);//使能定时器更新

       
        TIM_Cmd(TIM7,ENABLE);//使能定时器

        NVIC_InitStruct.NVIC_IRQChannel=TIM7_IRQn;
        NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority=0;
        NVIC_InitStruct.NVIC_IRQChannelSubPriority=0;
        NVIC_InitStruct.NVIC_IRQChannelCmd=ENABLE;
        NVIC_Init(&NVIC_InitStruct);
}

定时器7中断使led翻转状态
void TIM7_IRQHandler()
{
if(TIM_GetITStatus(TIM7,TIM_IT_Update)!=SET)
    {
                 TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
           LED=!LED;
    }
}