STM32 MCU Learning (5) Timer Interrupt Experiment

*	
* Software function: timer interrupt experiment
*
*/
#include "stm32f10x.h"
#include "delay.h"


void RCC_Configuration(void);
void GPIO_Configuration(void);
void NVIC_Configuration(void);
void TIM3_Configuration(u16 arr,u16 psc);

/*
Function: int main(void)
Function: main function
Parameters: None
Returns: None
/
int main(void)
{
  RCC_Configuration();
  GPIO_Configuration();
  NVIC_Configuration();
  TIM3_Configuration(4999,7199); //10Khz counting frequency, 500ms when counting to 5000  
  //delay_init(72);
  GPIO_ResetBits(GPIOB,GPIO_Pin_0);
  while(1);   
}


/*
Function: void RCC_Configuration(void)
Function: Reset and clock control configuration
Parameters: None
Returns: None
/
void RCC_Configuration(void)
{
  ErrorStatus HSEStartUpStatus; //Define the external high-speed crystal startup status enumeration variable
  RCC_DeInit(); //Reset RCC external device registers to default values
  RCC_HSEConfig(RCC_HSE_ON); //Turn on the external high-speed crystal oscillator
  HSEStartUpStatus = RCC_WaitForHSEStartUp(); //Wait for the external high-speed clock to be ready
  if(HSEStartUpStatus == SUCCESS) //The external high-speed clock is ready
  {
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable); // Enable the FLASH pre-read buffer function to speed up the reading of FLASH. Required usage in all programs. Location: in the RCC initialization sub-function, after the clock starts
    FLASH_SetLatency(FLASH_Latency_2); //Flash operation delay
      	
    RCC_HCLKConfig(RCC_SYSCLK_Div1); //Configure AHB (HCLK) clock equal to == SYSCLK
    RCC_PCLK2Config(RCC_HCLK_Div1); //Configure APB2(PCLK2) clock==AHB clock
    RCC_PCLK1Config(RCC_HCLK_Div2); //Configure APB1(PCLK1) clock == AHB1/2 clock
         
    RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9); //Configure PLL clock == external high-speed crystal clock * 9 = 72MHz
    RCC_PLLCmd(ENABLE); //Enable PLL clock
   
    while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET) //Wait for PLL clock to be ready
    {
    }
    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK); //Configure system clock = PLL clock
    while(RCC_GetSYSCLKSource() != 0x08) //Check if PLL clock is used as system clock
    {
    }
  }
  
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE); //Enable GPIOB and AFIO clocks
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //Clock enable

}

/*
Function: void GPIO_Configuration(void）
Function: GPIO configuration
Parameters: None
Returns: None
/
void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure; //Define GPIO initialization structure

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Speed ​​= GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_Init(GPIOB, &GPIO_InitStructure); //PB is used to output and control the LED light

}


void NVIC_Configuration(void) //Interrupt grouping and priority configuration For details, see "STM32 Function Description (Chinese).pdf" P165
{
    NVIC_InitTypeDef NVIC_InitStructure;
	NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3 interrupt
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //Preempt priority level 0
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //From priority level 3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ channel is enabled
	NVIC_Init(&NVIC_InitStructure); //Initialize NVIC registers
}

void TIM3_Configuration(u16 arr,u16 psc) //TIM3 timer configuration   
{
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	TIM_TimeBaseStructure.TIM_Period = arr; //Set the value of the auto-reload register period to load the activity at the next update event	
	TIM_TimeBaseStructure.TIM_Prescaler =psc; //Set the prescaler value used as the TIMx clock frequency divisor
	TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //Set clock division: TDTS = Tck_tim
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM up counting mode
	TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //Initialize the time base unit of TIMx according to the specified parameters
 	/*((1+7199[TIM_Prescaler] )/72M)*(1+4999[TIM_Period] )=500,000us=500ms */

	TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE); //Enable the specified TIM3 interrupt and allow update interrupt
	TIM_Cmd(TIM3, ENABLE); //Enable TIMx
}

//Timer 3 interrupt service routine
void TIM3_IRQHandler(void) //TIM3 interrupt
{
	if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) //Check whether TIM3 update interrupt occurs
		{
		TIM_ClearITPendingBit(TIM3, TIM_IT_Update ); //Clear TIMx update interrupt flag
		if(!GPIO_ReadInputDataBit(GPIOB,GPIO_Pin_0)) GPIO_SetBits(GPIOB,GPIO_Pin_0);
		else GPIO_ResetBits(GPIOB,GPIO_Pin_0);
	}
}