STM32F746ZGT and interrupt on button pressing always fires

[Sagiv_Alia]

Hello there, as a way to study embedded programming I decided to perform various tasks on the board, including firing an interrupt on button pressing to light up the 3 user LEDs.

I got stuck, the interrupt always fires.

In the beginning I tried debugging it myself, using the reference manual, user manual, arm architecture reference manual and the schematic, in the end I got desperate and tried debugging with chatgpt.

As a way of research, I didn't use HAL and wrote it pretty much myself.

The LEDs light up alright on their own, it's just the interrupt that always fires, maybe because I use the debug option and the step in and step over?

Thank you.

Here is the code:

#define RCC_AHB1ENR1 (int*)(0x40023830)

#define RCC_BASE ((int*)(0x40023800))

#define EXTI_BASE ((int*)(0x40013C00))

#define SYSCFG_BASE ((int*)(0x40013800))

#define GPIOB_BASE ((int*)(0x40020400))

#define GPIOC_BASE ((int*)(0x40020800))

#define NVIC_ISER1 ((int*)(0xE000E104))

typedef struct {
	unsigned int RCC_CR;
	unsigned int RCC_PLLCFGR;
	unsigned int RCC_CFGR;
	unsigned int RCC_CIR;
	unsigned int RCC_AHB1RSTR;
	unsigned int RCC_AHB2RSTR;
	unsigned int RCC_AHB3RSTR;
	unsigned int RES1;
	unsigned int RCC_APB1RSTR;
	unsigned int RCC_APB2RSTR;
	unsigned int RES2;
	unsigned int RES3;
	unsigned int RCC_AHB1ENR;
	unsigned int RCC_AHB2ENR;
	unsigned int RCC_AHB3ENR;
	unsigned int RES4;
	unsigned int RCC_APB1ENR;
	unsigned int RCC_APB2ENR;
	unsigned int RES5;
	unsigned int RES6;
	unsigned int RCC_AHB1LPENR;
	unsigned int RCC_AHB2LPENR;
	unsigned int RCC_AHB3LPENR;
	unsigned int RES7;
	unsigned int RCC_APB1LPENR;
	unsigned int RCC_APB2LPENR;
	unsigned int RES8;
	unsigned int RES9;
	unsigned int RCC_BDCR;
	unsigned int RCC_CSR;
	unsigned int RES10;
	unsigned int RES11;
	unsigned int RCC_SSCGR;
	unsigned int RCC_PLLI2SCFGR;
	unsigned int RCC_PLLSAICFGR;
	unsigned int RCC_DCKCFGR1;
	unsigned int DCKCFGR2;

} RCC;


typedef struct {
	volatile unsigned int MODER;
	volatile unsigned int OTYPER;
	volatile unsigned int OSPEEDR;
	volatile unsigned int PUPDR;
	volatile unsigned int IDR;
	volatile unsigned int ODR;
	volatile unsigned int BSRR;
	volatile unsigned int LCKR;
	volatile unsigned int AFRL;
	volatile unsigned int AFRH;
} UGPIO;


typedef struct {

	volatile unsigned int EXTI_IMR;
	volatile unsigned int EXTI_EMR;
	volatile unsigned int EXTI_RTSR;
	volatile unsigned int EXTI_FTSR;
	volatile unsigned int EXTI_SWIER;
	volatile unsigned int EXTI_PR;



} EXTI;
typedef struct {
	volatile unsigned int SYSCFG_MEMRMP;
	volatile unsigned int SYSCFG_PMC;
	volatile unsigned int SYSCFG_EXTICR1;
	volatile unsigned int SYSCFG_EXTICR2;
	volatile unsigned int SYSCFG_EXTICR3;
	volatile unsigned int SYSCFG_EXTICR4;
	volatile unsigned int SYSCFG_CMPCR;

} SYSCFG;

RCC* rcc = (RCC*)RCC_BASE;

	  EXTI* exti = (EXTI*)EXTI_BASE;
	  SYSCFG* syscfg = (SYSCFG*)SYSCFG_BASE;

	  UGPIO* gpiob = (UGPIO*)GPIOB_BASE;
	  UGPIO* gpioc = (UGPIO*)GPIOC_BASE;


void EXTI15_10_IRQHandler(){


	if (exti->EXTI_PR & (1 << 13))
	    {
	        exti->EXTI_PR = (1 << 13); // clear pending

	        gpiob->BSRR |= (1 << 7);

	        	gpiob->BSRR |= (1 << 14);

	        	gpiob->BSRR |= 1;
	    }



}


int main(void)
{


		//PC13 -> EXTI15



	  rcc->RCC_AHB1ENR |= (1 << 1); //GPIOB CLOCK GATING
	  rcc->RCC_AHB1ENR |= (1 << 2); //GPIOC CLOCK GATING
	  rcc->RCC_APB2ENR |= (1 << 14); //SYSCFG CLOCK GATING

	  gpiob->MODER &= ~(3 << 14);  // clear
	 	  gpiob->MODER |=  (1 << 14);  // set
	 	  gpiob->MODER &= ~(3 << 28);  // clear
	 	  gpiob->MODER |=  (1 << 28);  // set
	 	  gpiob->MODER &= ~2;  // clear
	 	  gpiob->MODER |=  1;  // set


	 	  //-------
	 	  gpioc->MODER &= ~(3 << (13 * 2));
	 	  // 0000 0000 0000 0000 0000 0000 0000 0011
	 	  // 0000 1100 0000 0000 0000 0000 0000 0000
	 	  // NOT = 1111 0011 1111 1111 1111 1111 1111 1111
	 	 gpioc->PUPDR &= ~(3 << (13 * 2));
	 	 //gpioc->PUPDR |=  (1 << (13 * 2));
	 	//gpioc->PUPDR |=  (2 << (13*2));

	 	syscfg->SYSCFG_EXTICR4 &= ~(0xF << 12);  // clear
	 	syscfg->SYSCFG_EXTICR4 |=  (0x2 << 12);  // port C
	 	 //gpioc->PUPDR |= (1 << (15 * 2));  // pull-up
	  exti->EXTI_IMR  |= (1 << 13);
	  exti->EXTI_FTSR |= (1 << 13);
	  exti->EXTI_RTSR &= ~(1 << 13);
	  exti->EXTI_PR = (1 << 13);

	  *NVIC_ISER1 |= (1 << 8);
	  
	  for (int i = 0; i < 10; i++)
	  {
		  int a = gpioc->IDR & (1 << 15);
		  int x = 1;
		  int y=2;
	  }

	  //40 47 settable EXTI15_10 EXTI Line[15:10] interrupts 0x0000 00E0




    /* Loop forever */
	for(;;)
	{

			  //gpiob->BSRR |= (1 << 23);
			  //gpiob->BSRR &= ~(1 << 7);
			  //for(int i =0; i < 1000000; i++);

	}

}