main.c

stm32初级例程

/*----------------------------------------------------------------------------
例子使用TIM4,的通道3，通道4产生2个固定占空比的PWM脉冲，其中
通道 3（PB8）产生占空比50% 的PWM脉冲
通道 4（PB9）产生占空比25% 的PWM脉冲
本例最好使用示波器观察不同的占空比波形

 *---------------------------------------------------------------------------*/

/* Includes ------------------------------------------------------------------*/
#define SYS_GLOBALS
#include "include.h"


TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;
u16 CCR1_Val = 2047;
u16 CCR2_Val = 1535;
u16 CCR3_Val = 1023;
u16 CCR4_Val = 511;
uint32  TIM_Period;

unsigned short Ccr = 0;                           // Capture , Compare value
int Dir = 1;                           // in- decrease CCR

/* Private function prototypes -----------------------------------------------*/
void RCC_Configuration(void);
void NVIC_Configuration(void);
void GPIO_Configuration(void);
void PWM_Configuration(void);

/* Private functions ---------------------------------------------------------*/

/*------------------------------------------------------------------------------
  Timer4 Update Interrupt Handler
  //考虑到效率问题，中断函数里面仍然直接操作寄存器
 *------------------------------------------------------------------------------*/
void TIM4_IRQHandler(void)
{
   if (TIM4->SR & (1 << 0))
   {
      // UIF set?
      // lower limit reached ? move up
      //判断占空比到最小
      if (Ccr == 0)
         Dir = 1;                     
      // upper limit reached ? move down
      //判断占空比到最大
      if (Ccr == 100)
         Dir = -1;
      Ccr = Ccr + Dir;   
      TIM4->CCR3 = Ccr;  // change ccr
      TIM4->CCR4 = 100 - Ccr;  // change ccr

      TIM4->SR &= ~(1 << 0);                          // clear UIF flag
   }
} // end TIM4_IRQHandler

void delay(uint32 time)
{uint32 i, j;
   
   for(i=0; i<time; i++)
   {
      for(j=0; j<14000; j++);
   }
}

/*******************************************************************************
* Function Name  : main
* Description    : Main program.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
int main(void)
{
#ifdef DEBUG
  debug();
#endif

  /* System Clocks Configuration */
  RCC_Configuration();//配置系统时钟   

  GPIO_Configuration();//配置GPIO
  
  /* NVIC configuration */
  NVIC_Configuration();//配置中断

  PWM_Configuration();
  while (1)
  {
  	
  }
  
}

//PWM初始化
void PWM_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
  
  
  /* GPIOB clock enable */
  //GPIOB使用的RCC时钟使能
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO, ENABLE);

  //配置使用的GPIO
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8|GPIO_Pin_9;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//GPIO_Mode_Out_PP;//;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GPIOB, &GPIO_InitStructure);
  
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
  
  /* Time base configuration */
	TIM_TimeBaseStructure.TIM_Period = 100-1;//1000; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值	 80K
	TIM_TimeBaseStructure.TIM_Prescaler =7200-1; //设置用来作为TIMx时钟频率除数的预分频值
	TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
	TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
	
	/* Output Compare Active Mode configuration: Channel1 */
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //选择定时器模式:TIM脉冲宽度调制模式2
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
	TIM_OCInitStructure.TIM_Pulse = 0; //设置待装入捕获比较寄存器的脉冲值
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高
	TIM_OC3Init(TIM4, &TIM_OCInitStructure);  //根据TIM_OCInitStruct中指定的参数初始化外设TIMx
	TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);  //使能TIMx在CCR2上的预装载寄存器
	
	TIM_OC4Init(TIM4, &TIM_OCInitStructure);  //根据TIM_OCInitStruct中指定的参数初始化外设TIMx
	TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable);  //使能TIMx在CCR2上的预装载寄存器
	
	TIM_ARRPreloadConfig(TIM4, ENABLE); //使能TIMx在ARR上的预装载寄存器
	
	/* TIM4 enable counter */
	TIM_Cmd(TIM4, ENABLE);  //使能TIMx外设
		
	//TIM4->DIER = 0x0001;                             // enable interrupt
  //NVIC->ISER[0] |= (1 << (TIM4_IRQChannel & 0x1F));     // enable interrupt
	
	//使能更新中断
	TIM_ITConfig(TIM4, TIM_IT_Update, ENABLE);
	//配置中断
	NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQChannel;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}


/*******************************************************************************
* Function Name  : RCC_Configuration
* Description    : Configures the different system clocks.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_Configuration(void)
{ErrorStatus HSEStartUpStatus;   
  
  /* RCC system reset(for debug purpose) */
  RCC_DeInit();

  /* Enable HSE */
  RCC_HSEConfig(RCC_HSE_ON);//使能外部时钟 

  /* Wait till HSE is ready */
  HSEStartUpStatus = RCC_WaitForHSEStartUp();//等待外部时钟就绪

  if(HSEStartUpStatus == SUCCESS)
  {
    /* Enable Prefetch Buffer 启用预取缓冲器 */
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);

    /* Flash 2 wait state FLASH设置2个等待周期*/
    FLASH_SetLatency(FLASH_Latency_2);
 
    /* HCLK = SYSCLK 设置系统设置*/
    RCC_HCLKConfig(RCC_SYSCLK_Div1); 
  
    /* PCLK2 = HCLK PCLK2时钟=主时钟*/
    RCC_PCLK2Config(RCC_HCLK_Div1); 

    /* PCLK1 = HCLK/2 PCLK1时钟为主时钟1/2*/
    RCC_PCLK1Config(RCC_HCLK_Div2);

    /* PLLCLK = 8MHz * 9 = 72 MHz 设置时钟为72M*/
    RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);

    /* Enable PLL 使能PLL*/ 
    RCC_PLLCmd(ENABLE);

    /* Wait till PLL is ready 等待PLL工作稳定*/
    while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
    {
    }

    /* Select PLL as system clock source 选择PLL做为系统时钟源*/
    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

    /* Wait till PLL is used as system clock source 准备就绪，开始干活*/
    while(RCC_GetSYSCLKSource() != 0x08)
    {
    }
  }
}

/*******************************************************************************
* Function Name  : GPIO_Configuration
* Description    : Configures the different GPIO ports.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  
  /* Enable GPIO_LED clock */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);//使能GPIO时钟
  //LED_init-------------------------------------------------------

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_Init(GPIOC, &GPIO_InitStructure);			 //设置GPIO为输出
  
}

/*******************************************************************************
* Function Name  : NVIC_Configuration
* Description    : Configures Vector Table base location.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void NVIC_Configuration(void)
{

//#ifdef  VECT_TAB_RAM
#if defined (VECT_TAB_RAM)
  /* Set the Vector Table base location at 0x20000000 */ 
  NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0); //设置中断向量在RAM中
//#elif defined(VECT_TAB_FLASH_IAP)
//  NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x2000);
#else  /* VECT_TAB_FLASH  */
  /* Set the Vector Table base location at 0x08000000 */ 
  NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0); //设置中断向量在FLASH中  
#endif


}




#ifdef  DEBUG
/*******************************************************************************
* Function Name  : assert_failed
* Description    : Reports the name of the source file and the source line number
*                  where the assert_param error has occurred.
* Input          : - file: pointer to the source file name
*                  - line: assert_param error line source number
* Output         : None
* Return         : None
*******************************************************************************/
void assert_failed(u8* file, u32 line)
{ 
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

  /* Infinite loop */
  while (1)
  {
  }
}
#endif

/******************* (C) COPYRIGHT 2008 STMicroelectronics *****END OF FILE****/