STM32- Timerinterrupt

#include <stm32f10x_lib.h>                    // STM32F10x Library Definitions

int irupt=0;

void syti_wait(void)

{

  while( (SysTick->CTRL & 0x10000 ) == 0 ){}

}

void TIM2_UP_IRQHandler (void) {

  if ((TIM2->SR & 0x0001) != 0)                       // check interrupt source

   {

    irupt=1;

      TIM2->SR &= ~(1<<0);                            // clear UIF flag

  }

} // end TIM1_UP_IRQHandler

int main (void)

{   

  unsigned short n;

  RCC->APB2ENR |= 0x4;                               // Port A mit Takt versorgen

  GPIOA->ODR |= 0x22;                                // PA5,PA1:    Output

  RCC->APB1ENR |= 0x01;                              // Timer 2 mit Takt versorgen

  // TIM2 Control Register

  // ARPE:

  // CMS: Edge-aligned mode           (reset value, nicht extra zu setzen)

  // DIR: upcounter               (reset value, nicht extra zu setzen)

  // OPM: 1, one pulse mode

  // URS: 1, only overflow/underflow generates an update interrupt

  // UDIS: UEV enabled             (reset value, nicht extra zu setzen)

  // CEN: Counter Enable, nach Bedarf setzen (OPM ist aktiviert!!!)

//  TIM2->CR1 |= (1<<3);                              // OPM setzen

  TIM2->CR1 |= (1<<2);                                // URS

  // TIM2 Prescaler

  // delta_t_Timer: 1ms -> f_Timer: 1000 Herz = 1MHz

  // f_APD : 72MHz (36MHz * 2)

  // => reload = 72MHz / 1MHz = 72

  //    72 - 1 = 71  TIM2->PSC = 71;

  TIM2->PSC = 71;

  // TIM2 Counter Value

  TIM2->CNT = 0;

  // TIM2 Auto Reload Value

  // 50.000 * 1/1000s = 5s

  TIM2->ARR = 50000;

  // INTERRUPT KONFIGURATION

  // TIM2-Interrupt: Interrupt Nr. 28 (Aus Vector Table, S. 197 reference manual)

  // CMSIS Mapping: ISER[0], ICER[0], ISPR[0], ICPR[0], IABR[0]: CMSIS (Cortex-M3 programming manual)

  NVIC->ISER[0] |= (1 << TIM2_IRQChannel);

  TIM2->CR1 |= 0x01;

  SysTick->CTRL |= 0x4;                           // SysTick aktivieren

  SysTick->LOAD = 800000;                 

  SysTick->CTRL |= 0x1;                           // SysTick starten

  for(n=0; n<1000; n++)

  {

    if (irupt==0)                                // Falls kein Timer-Interrupt

    {

      GPIOA->CRL = 0x44344444;          // LED1 an PA5 an: Output, Push-Pull, 50MHz

      syti_wait();

      GPIOA->CRL = 0x44444444;          // LED1 aus, Port resetten.

      syti_wait();

      GPIOA->CRL = 0x44444434;          // LED2 an PA1 an: Output, Push-Pull, 50MHz

      syti_wait();

      GPIOA->CRL = 0x44444444;          // LED2 aus, Port resetten.

      syti_wait();

    }

    else

    {

      GPIOA->CRL = 0x44344434;          // LED1 & LED2 an

      syti_wait();                      // Warten

      syti_wait();

      syti_wait();

      syti_wait();

      syti_wait();

      syti_wait();

      GPIOA->CRL = 0x44444444;          // LED1  & LED2 aus

      syti_wait();

      irupt=0;      

    }

  }

  SysTick->CTRL &= 0x0;                // SysTick stoppen

  while(1);

}