STM32_timer_and_interrupt

main.cpp

#include "stm32f10x.h"

//core peripherals of the CPU .. address taken from the data sheet
#define NVIC_ISER0 *((unsigned int*)0xE000E100)

int main()
{
	//NVIC_InitTypeDef TIM2_INT;
	//Reset and clock control : enabling the clock source for the timer2
	RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
	//Reset and clock control : enabling the GPIO : PC13 for LED blinking.
	RCC->APB2ENR |= RCC_APB2ENR_IOPCEN;

	//In output push-pull mode , 50MHz maximum operating frequency
	GPIOC->CRH |= GPIO_CRH_MODE13_0|GPIO_CRH_MODE13_1;

	//To stop the timer on arrival of breakpoint (optional)
	//DBGMCU->CR |= DBGMCU_CR_DBG_TIM2_STOP;

	//attempting to generate a clock of 1Hz
	TIM2->PSC = 36000;
	TIM2->ARR = 2000;

	//other settings are default.
	//counter is now enabled
	TIM2->CR1 |= TIM_CR1_CEN;

	//setting up the NVIC interrupt vector
	//it can also be setup using NVIC structure (NVIC_InitTypeDef) provided in library
	NVIC_ISER0 |= (1<<TIM2_IRQn);

	//update interrupt enable
	//no trigger event is used ..
	TIM2->DIER |= TIM_DIER_UIE;

	while(1);
	//interrupt service routine definition is present in stm32f1xx_it.c
	//interrupt service routine prototype is present in stm32f1xx_it.h
	//interrupt service routine name is present in startup_stm32f10x_md.s
}

stm32f1xx.c

#include "stm32f1xx_it.h"
#include "stm32f10x.h"
uint32_t counter;

void TIM2_IRQHandler(void)
{
	//clearing the update interrupt flag of the register
	TIM2->SR &= ~TIM_SR_UIF;

	static uint32_t counter = 0;
	counter++;

	if(counter%2==0)
	{
		GPIOC->BSRR = (1<<29);
	}
	else
	{
		GPIOC->BSRR = (1<<13);
	}
}

stm32f1xx.h

#ifndef __STM32F1XX_IT_H
#define __STM32F1XX_IT_H

#ifdef __cplusplus
 extern "C" {
#endif 

/* Includes ------------------------------------------------------------------*/
#include "stm32f10x.h"

/* Exported types ------------------------------------------------------------*/
/* Exported constants --------------------------------------------------------*/
/* Exported macro ------------------------------------------------------------*/
/* Exported functions ------------------------------------------------------- */

#define NVIC_ICPR0 *((unsigned int*)0xE000E280)
#define NVIC_ISER0 *((unsigned int*)0xE000E100)

void NMI_Handler(void);
void HardFault_Handler(void);
void MemManage_Handler(void);
void BusFault_Handler(void);
void UsageFault_Handler(void);
void SVC_Handler(void);
void DebugMon_Handler(void);
void PendSV_Handler(void);
void SysTick_Handler(void);
void EXTI15_10_IRQHandler(void);

//extra interrupt handler : added by subha sarkar
void TIM2_IRQHandler(void);


#ifdef __cplusplus
}
#endif

#endif