STM32学习问题记录（11） - 呼吸灯

     昨天看了PWM的产生，今天就来尝试一下呼吸灯的制作，如果PWM理解比较透彻的话，呼吸灯的制作就十分简单，原理很简单，就是改变CCR寄存器的值，来按时间输出占空比不同的方波即可，原理十分简单，在这里附上定时器输出PWM的代码和中断函数中的代码（其中呼吸灯有个数组文件需要用matlab生成），在此也不多加赘述。

   TIM3_Breathing_Init();

void TIM3_Breathing_Init(void)
{
	TIM3_GPIO_Config();
	TIM3_Mode_Config();	
}

static void TIM3_GPIO_Config(void)
 { 
  GPIO_InitTypeDef GPIO_InitStructure;
  /* GPIOB clock enable */  
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE); 
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0 ; 
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;     
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);
}

static void TIM3_Mode_Config(void)
{
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
	TIM_OCInitTypeDef  TIM_OCInitStructure;									
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); 						 
  TIM_TimeBaseStructure.TIM_Period = 255;       							
  TIM_TimeBaseStructure.TIM_Prescaler = 1999;	    							
  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ;		
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  	
  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

 
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;	    				
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;	
  TIM_OCInitStructure.TIM_Pulse = 0;										  				
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;  	

  TIM_OC3Init(TIM3, &TIM_OCInitStructure);	 										
  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);						
  TIM_ARRPreloadConfig(TIM3, ENABLE);			 									
  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);                   										
	TIM_ITConfig(TIM3,TIM_IT_Update, ENABLE);												
	NVIC_Config_PWM();	
	
}

static void NVIC_Config_PWM(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
  
  /* Configure one bit for preemption priority */
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
  
  NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}

//中断函数

void TIM3_IRQHandler(void)
{	
	static uint8_t pwm_index = 0;			
	static uint8_t period_cnt = 0;			
	if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)	//TIM_IT_Update
 	{			
			period_cnt++;
			if(period_cnt >= 10)													{
				
				TIM3->CCR3 = indexWave[pwm_index];	
				pwm_index++;															
				if( pwm_index >=  40)												{
					pwm_index=0;								
				}
				
				period_cnt=0;												
		}
		TIM_ClearITPendingBit (TIM3, TIM_IT_Update);	
	}
}

uint8_t indexWave[] = {1,1,2,2,3,4,6,8,10,14,19,25,33,44,59,80,
	107,143,191,255,255,191,143,107,80,59,44,33,25,19,14,10,8,6,4,3,2,2,1,1};