EEM-465 Gömülü Sistemler

2022-2023 Güz Dönemi Ders 7

SysTick Timer (Zamanlayıcı)

Meşgul bekleme yöntemi

#include "stm32f4xx.h"
int main(){
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
  GPIOD->MODER |= GPIO_MODER_MODER14_0;
  
    // 1 saniye gecikme icin
  SysTick->LOAD = 2000000;
  
    // 100 hz frekansında sinyal için
  // SysTick->LOAD = 10000;
  SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
  while(1){
    GPIOD->ODR |= GPIO_ODR_OD14;
    while(!(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk));
    
    GPIOD->ODR &= ~GPIO_ODR_OD14;
    while(!(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk));
  }
}

CLK_SOURCE bitinin etkisi

#include "stm32f4xx.h"
int main(){
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
  GPIOD->MODER |= GPIO_MODER_MODER14_0;
  //5ms gecikme
  SysTick->CTRL |= SysTick_CTRL_CLKSOURCE_Msk;
  SysTick->LOAD = 80000;
  SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
  while(1){
    GPIOD->ODR |= GPIO_ODR_OD14;
    while(!(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk));
    
    GPIOD->ODR &= ~GPIO_ODR_OD14;
    while(!(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk));
  }
}

Yoklama yöntemi, xor ile LED yakma ve söndürme

#include "stm32f4xx.h"
int main(){
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
  GPIOD->MODER |= GPIO_MODER_MODER14_0;
  //0.5 sn gecikme
  SysTick->CTRL |= SysTick_CTRL_CLKSOURCE_Msk;
  SysTick->LOAD = 8000000;
  SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
  while(1){
    if(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk){
      GPIOD->ODR ^= GPIO_ODR_OD14;
    }
        //diger kodlamalar buraya eklenebilir.
  }
}

Yoklama yöntemi, ODR yazmacının kontrolü ile LED yakma söndürme

#include "stm32f4xx.h"
int main(){  
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
  GPIOD->MODER |= GPIO_MODER_MODER14_0;
  //0.5 sn gecikme
  SysTick->CTRL |= SysTick_CTRL_CLKSOURCE_Msk;
  SysTick->LOAD = 8000000;
  SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
  while(1){
    if(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk){
      if(GPIOD->ODR & GPIO_ODR_OD14)
        GPIOD->ODR &= ~GPIO_ODR_OD14;
      else
        GPIOD->ODR |= GPIO_ODR_OD14;
    }
        //diger kodlamalar buraya eklenebilir.
  }
}

Kesme ile sürenin bittiğinin tespiti

#include "stm32f4xx.h"
void SysTick_Handler(void);
void SysTick_Handler(void){
  if(GPIOD->ODR & GPIO_ODR_OD14)
    GPIOD->ODR &= ~GPIO_ODR_OD14;
  else
      GPIOD->ODR |= GPIO_ODR_OD14;
}
int main(){  
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
  GPIOD->MODER |= GPIO_MODER_MODER14_0;
  NVIC_EnableIRQ(SysTick_IRQn);
  //0.1 sn gecikme
  SysTick->CTRL |= SysTick_CTRL_CLKSOURCE_Msk;
  SysTick->LOAD = 160000;
  SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;
  SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
  while(1){
    //diger kodlamalar
  }
}