STM32F4 EXTI Problem

#include "ch.h"

#include "hal.h"

#include "test.h"

#define ARM_MATH_CM4

#include "arm_math.h"

#include "irqconf.h"

#include "usbcfg.h"

// Code für USB-Kommunikation nicht enthalten

// Declare & initialize IRQ counter

static uint32_t irq_cnt = 0;

// IRQ function

void EXTI0_IRQHandler(void) {

  palSetPad(GPIOD,GPIOD_LED3);

  /* Make sure that interrupt flag is set.

   ((uint32_t)0x00001) equals EXTI Line 0*/

  if ((EXTI->PR & (uint32_t)0x00000001) != (uint32_t)RESET){

    palTogglePad(GPIOD,GPIOD_LED5);

    // Do the actual work

    irq_cnt++;

    // Clear interrupt flag for EXTI0

    EXTI->PR |= EXTI_PR_PR0;

  }

}

int main(void) {

  halInit();

  chSysInit();

  palSetPadMode(GPIOA, GPIOA_BUTTON, PAL_MODE_INPUT);

  irq_init();

  while (true) {

    chprintf((BaseSequentialStream *)&SDU1,"IRQcounter: %u \r\n", IRQcounter);

    }

    chThdSleepMilliseconds(500);

  }

}

#include "ch.h"

#include "hal.h"

void irq_init(void)

{

  // IO port A clock enable

  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;

  // System configuration controller clock enable

  RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN;

  // Enable IRQ for ext. signals, line EXTI0_IRQn. Enables the handling for the

  // given interrupt request (IRQ#)

  NVIC_EnableIRQ(EXTI0_IRQn);

  // Clear EXTI0 bit field

  SYSCFG->EXTICR[0] &= ~(SYSCFG_EXTICR1_EXTI0);

  // EXTI x configuration. Select PA to make IRQ EXTI0

  SYSCFG->EXTICR[0] |= SYSCFG_EXTICR1_EXTI0_PA;

  // Rising trigger event configuration bit of line A

  EXTI->RTSR |= EXTI_RTSR_TR0;

  // Enable interrupt on EXTI0

  EXTI->IMR |= EXTI_IMR_MR0;

//  EXTI->SWIER |= EXTI_SWIER_SWIER0;

  //END OF IRQ STUFF

}

#ifndef IRQ_H

#define IRQ_H

void irq_init(void);

#endif /* IRQ_H */