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problem with the dimensioning of the resistors pull-up?

Question asked by capasso.ornella on Nov 13, 2012
Latest reply on Nov 14, 2012 by capasso.ornella
Hi, I have enabled external interrupt (EXTI) by connecting to pin PA4 a button, with its pull-up (I also tried the pull down) but when I pressed the button sometimes is performed twice Iterrupt routine (or more times)! I think it's a problem of dimensioning of the resistors, There has never happened to you? and how you solved it? maybe it's because I neglect the resistance offered by pin PA4, can you tell me that resistance have the pin or what is the average current consumption of the pin?


the code I used is:


//EXTI CONFIG
     
void Exti_Config(void)
{
  EXTI_InitTypeDef   EXTI_InitStructure;
  GPIO_InitTypeDef   GPIO_InitStructure;
  NVIC_InitTypeDef   NVIC_InitStructure;
 
  /* Enable GPIOA clock */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
  /* Enable SYSCFG clock */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
   
  /* Configure PA0 pin as input floating */
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
 
  /* Connect EXTI Line0 to PA5 pin */
  SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource4);
 
  /* Configure EXTI Line0 */
  EXTI_InitStructure.EXTI_Line = EXTI_Line4;
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;//EXTI_Trigger_Rising;  Falling
  EXTI_InitStructure.EXTI_LineCmd = ENABLE;
  EXTI_Init(&EXTI_InitStructure);
 
  /* Enable and set EXTI Line0 Interrupt to the lowest priority */
  NVIC_InitStructure.NVIC_IRQChannel = EXTI4_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x01;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x01;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}


//Interrupt routine
void EXTI4_IRQHandler(void)
{
  if(EXTI_GetITStatus(EXTI_Line4)==SET)
  {
         
    /* Clear the EXTI line 0 pending bit */
    EXTI_ClearITPendingBit(EXTI_Line4);
         
        k=k+1;
        STM_EVAL_LEDOn(LED4);
     
  }
            if(k==2){
 STM_EVAL_LEDOff(LED4);
  k=0;

}
}

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