EXTI15_10_IRQn triggered constantly - STM32L4R5ZI

[KHuyn]

Hi, I am trying to write an interrupt code to trigger LED(PB14) using user button on my NUCLEO board(PC13). however, as I observed from the debugger, pending bit for line 13 constantly at 1 without pushing the button at all.

The EXTI->PR1 = 1<<13 still executed but it can't clear the pending bit.

Could someone point out my problem? here is my code.

Thank you.

/*--Header--------------------------------------------------------------------------------*/
#include <stdio.h>
#include <stdint.h>
#include "stm32l4r5xx.h"
/*--Define--------------------------------------------------------------------------------*/
/*--Global-Variable---------------------------------------------------------------------- */
/*--Function Prototypes-------------------------------------------------------------------*/
void initPort (void);
void Blink(void);
/*--Main----------------------------------------------------------------------------------*/
int main()
{
	initPort();
  while(1)
  {
 
  }
} // EO Main
 
/*--Function------------------------------------------------------------------------------*/
/************************************************/
/*             Name: initPort                   */
/*-Initiating PC13 as input/interrupt           */
/*-Initiating PB14 as LED red	                */
/*                                              */
/************************************************/
void initPort(void)
{
	RCC->AHB2ENR |= 0x04;// Enable GPIO port D
	GPIOC->MODER &= ~(1<<26);
	GPIOC->MODER &= ~(1<<27); // Enable PC13 as input - Button
	EXTI->RTSR1 |= 0x1<<13; // Enable EXTI15-PD13 triggers in raising edge
	EXTI->IMR1 |= 0x1<<13; // Un-mask EXTI15 to enable the interrupt in PD13
	NVIC->ISER[1] |= 1<<8; //Enable EXTI15_10 - vector position 40
 
	RCC->AHB2ENR |= 1<<1; //Enable GPIO port B
	GPIOB->MODER &= ~(1<<29);
	GPIOB->MODER |= 1<<28; //Set PD14 as general output LED3
 
}
void Blink(void)
{
	GPIOB->ODR ^= 1<<14; // toggle pin PB14 - LED3
	for(int i=0; i<10000; i++);
}
void EXTI15_10_IRQHandler (void)
{
	if (EXTI->PR1 & 1<<13) // check if the pending register is on
		{
			EXTI->PR1 = 1<<13; // clear the pending register by writing 1 to it
		}
	Blink();
}

[berendi · Accepted solution]

Set the EXTI source in SYSCFG->EXTICR[].

At reset, all EXTI sources are mapped to GPIOA, so EXTI13 is triggered by edges on PA13. Which happens to be the SWDIO pin, so it is triggered every time the debugger probe makes some request. (disable the onboard debugger, it should stop blinking)

[KHuyn]

That's what I need. Thank you!

** remember to enable SYSCFG register in RCC**

[KHuyn]

/*--Header--------------------------------------------------------------------------------*/
#include <stdio.h>
#include <stdint.h>
#include "stm32l4r5xx.h"
/*--Define--------------------------------------------------------------------------------*/
/*--Global-Variable---------------------------------------------------------------------- */
/*--Function Prototypes-------------------------------------------------------------------*/
void initPort (void);
void Blink(void);
/*--Main----------------------------------------------------------------------------------*/
int main()
{
	initPort();
  while(1)
  {
 
  }
} // EO Main
 
/*--Function------------------------------------------------------------------------------*/
/************************************************/
/*             Name: initPort                   */
/*-Initiating PC13 as input/interrupt           */
/*-Initiating PB14 as LED red	                */
/*                                              */
/************************************************/
void initPort(void)
{
/*config user button PC13 as interrupt input*/
	RCC->AHB2ENR |= 0x04;// Enable GPIO port D
	GPIOC->MODER &= ~(1<<26);
	GPIOC->MODER &= ~(1<<27); // Enable PC13 as input - Button
 
	EXTI->RTSR1 |= 0x1<<13; // Enable EXTI15-PD13 triggers in raising edge
	EXTI->IMR1 |= 0x1<<13; // Un-mask EXTI15 to enable the interrupt in EXTI13 MUX
	NVIC->ISER[1] |= 1<<8; //Enable EXTI15_10 - vector position 40 in NVIC
 
	RCC->APB2ENR |= 0x01; //Enable SYSCFG register clock gate
	SYSCFG->EXTICR[3] &= ~(0x0F<<4);
	SYSCFG->EXTICR[3] |= 1<<5; // Select PC13 as interrupt trigger for EXTI13 line
 
/*config PB14 as red LED3 */
	RCC->AHB2ENR |= 1<<1; //Enable GPIO port B
	GPIOB->MODER &= ~(1<<29);
	GPIOB->MODER |= 1<<28; //Set PD14 as general output LED3
 
}
void Blink(void)
{
	GPIOB->ODR ^= 1<<14; // toggle pin PB14 - LED3
	for(int i=0; i<10000; i++);
}
void EXTI15_10_IRQHandler (void)
{
	if (EXTI->PR1 & 1<<13) // check if the pending register is on
		{
			EXTI->PR1 = 1<<13; // clear the pending register by writing 1 to it
		}
	Blink();
}

[Vmere.1]

This saved me a lot of time. Thank you