#define N 10
u8 IntFlag=0;
//-----
void INT1(void){
static cnt=0;
    .........
   if(++cnt>N){
      cnt=0;
      IntFlag=1;
   }
}
//-----
void SUB1(void){
   if(IntFlag){
      IntFlag=0;
      ...........
   }
}
//
int main(void){
    .......
   while(xxxx){
      .....
      SUB1();
   }

    ........
}

    NVIC_EnableIRQ(CMU_IRQn);// ненужное прерывание периферии
    NVIC_SetPendingIRQ(CMU_IRQn);

__ASM volatile ("svc 0");

*( volatile uint32_t *) 0xE000ED04 )|= 0x10000000;

//высокочастотное прерывание:
void INT1(void){
static cnt=0;
    .........
   if(++cnt>N){
      cnt=0;
      EXTI_GenerateSWInterrupt(EXTI_Line15);// "взвоим курок" - после выхода из INT1 произойдет вызов прерывания EXTI15_10  
   }
}

// программное прерывание:
void EXTI15_10_IRQHandler(void){
  if(EXTI_GetITStatus(EXTI_Line15) != RESET)  {
    SUB1();
    EXTI_ClearITPendingBit(EXTI_Line15); // Clear the EXTI line 15 pending bit
  }
}

// Настройки:
void Init_EXTI_SWI(void){
  EXTI_InitTypeDef   EXTI_InitStructure;
  NVIC_InitTypeDef   NVIC_InitStructure;

  /* Enable SYSCFG clock */
//  RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
  
  /* Configure EXTI Line15 */
  EXTI_InitStructure.EXTI_Line = EXTI_Line15;
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
  EXTI_InitStructure.EXTI_LineCmd = ENABLE;
  EXTI_Init(&EXTI_InitStructure);

  /* Enable and set EXTI15_10 Interrupt to the lowest priority */
  NVIC_InitStructure.NVIC_IRQChannel = EXTI15_10_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

  NVIC_Init(&NVIC_InitStructure);

}
// в настройке ВЧ прерывания приоритет повыше:
//  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x01;
//  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x01;

...
        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
                        // Setup SysTick Timer for 1 msec interrupts, lowest priority
      if (SysTick_Config(SystemCoreClock / 1000)) { while (1);} // Capture error
        NVIC_SetPriority(SysTick_IRQn,  4);  //    SysTick priority=4
       ..

      // uart
      NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
      NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
      ...
     // sw interrupt
     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
     ...
     // SPI, highest priority
     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    ...

        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
        NVIC_SetPriority(SPI2_IRQn,                1);  //    SPI priority=1
        NVIC_SetPriority(EXTI15_10_IRQn,       2);  //    SW interrupt priority=2
        NVIC_SetPriority(USART3_IRQn_IRQn,  3);  //    UART=3
        NVIC_SetPriority(SysTick_IRQn,            4);  //    SysTick priority=4