参考：STM32输入捕获模式设置并用DMA接收数据

PWM input mode

This mode is a particular case of input capture mode.

The procedure is the same except:

 Two ICx signals are mapped on the same TIx input.
 These 2 ICx signals are active on edges with opposite polarity.
 One of the two TIxFP signals is selected as trigger input and the slave mode controller is configured in reset mode.

For example, you can measure the period (in TIMx_CCR1 register) and the duty cycle (in TIMx_CCR2 register)

of the PWM applied on TI1 using the following procedure (depending on CK_INT frequency and prescaler value):

 Select the active input for TIMx_CCR1: write the CC1S bits to 01 in the TIMx_CCMR1 register (TI1 selected).
 Select the active polarity for TI1FP1 (used both for capture in TIMx_CCR1 and counter clear): write the CC1P and CC1NP bits to ‘0’ (active on rising edge).
 Select the active input for TIMx_CCR2: write the CC2S bits to 10 in the TIMx_CCMR1 register (TI1 selected).
 Select the active polarity for TI1FP2 (used for capture in TIMx_CCR2): write the CC2P and CC2NP bits to ‘1’ (active on falling edge).
 Select the valid trigger input: write the TS bits to 101 in the TIMx_SMCR register (TI1FP1 selected).
 Configure the slave mode controller in reset mode: write the SMS bits to 100 in the TIMx_SMCR register.
 Enable the captures: write the CC1E and CC2E bits to ‘1’ in the TIMx_CCER register.

STM32的PWM输入模式设置并用DMA接收数据

项目中需要进行红外学习,如果采用输入捕获的方式,因为定时器只能捕获上升沿或者下降沿,

所以只能获得周期,而不能得到具体的红外波的高低电平的时间.

所以采用PWM输入的方式进行捕获. 采用的是PA8脚,对应TIM1的通道1.

/*********************************************************************

 *             函数

 **********************************************************************/

/*********************************************************************

 *             接口函数:初始化红外学习模块

 **********************************************************************/

void inf_infrared_study_init( void )

{

  //初始化io口

  inf_init_io( );

  //初始化中断

  //inf_init_irq();

  //初始化定时器

  inf_init_timer( );

  //打开DMA

  inf_infrared_study_open_dma(  );

  //打开定时器

  inf_infrared_study_open_timer(  );

}

/*********************************************************************

 *             初始化io口

 **********************************************************************/

static void inf_init_io( void )

{

  //定义IO初始化结构体

  GPIO_InitTypeDef GPIO_InitStructure;

  //初始化时钟

  RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOB, ENABLE );

  //管脚初始化

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;

  //设置为输入

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

  //初始化

  GPIO_Init( GPIOA, &GPIO_InitStructure );

}

/*********************************************************************

 *             初始化中断

 **********************************************************************/

static void inf_init_irq( void )

{

  //定义外部中断结构体

  EXTI_InitTypeDef EXTI_InitStructure;

  //初始化中断脚复用时钟

  RCC_APB2PeriphClockCmd( RCC_APB2Periph_AFIO, ENABLE );

  //配置中断源

  GPIO_EXTILineConfig( GPIO_PortSourceGPIOB, GPIO_PinSource1 );

  // 配置下降沿触发

  EXTI_ClearITPendingBit( EXTI_Line1 );

  EXTI_InitStructure.EXTI_Line = EXTI_Line1;

  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;

  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

  EXTI_InitStructure.EXTI_LineCmd = ENABLE;

  EXTI_Init( &EXTI_InitStructure );

}

/*********************************************************************

 *             初始化定时器

 **********************************************************************/

static void inf_init_timer( void )

{

  //定义定时器结构体

  TIM_TimeBaseInitTypeDef timInitStruct;

  //输入捕获结构体

  TIM_ICInitTypeDef tim_icinit;

  //定义DMA结构体

  DMA_InitTypeDef DMA_InitStructure;

  //启动DMA时钟

  RCC_AHBPeriphClockCmd( RCC_AHBPeriph_DMA1, ENABLE );

  //DMA1通道配置

  DMA_DeInit( DMA1_Channel2 );

  //外设地址

  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) ( &TIM1->CCR1 );

  //内存地址

  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) Rx_Buf_Tim_Dma1;

  //dma传输方向单向

  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

  //设置DMA在传输时缓冲区的长度

  DMA_InitStructure.DMA_BufferSize = RX_LEN_TIM_DMA;

  //设置DMA的外设递增模式，一个外设

  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

  //设置DMA的内存递增模式

  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

  //外设数据字长

  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

  //内存数据字长

  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

  //设置DMA的传输模式

  //DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;

  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

  //设置DMA的优先级别

  DMA_InitStructure.DMA_Priority = DMA_Priority_High;

  //设置DMA的2个memory中的变量互相访问

  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

  DMA_Init( DMA1_Channel2, &DMA_InitStructure );

  //启动DMA时钟

  RCC_AHBPeriphClockCmd( RCC_AHBPeriph_DMA1, ENABLE );

  //DMA1通道配置

  DMA_DeInit( DMA1_Channel3 );

  //外设地址

  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) ( &TIM1->CCR2 );

  //内存地址

  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) Rx_Buf_Tim_Dma2;

  //dma传输方向单向

  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

  //设置DMA在传输时缓冲区的长度

  DMA_InitStructure.DMA_BufferSize = RX_LEN_TIM_DMA;

  //设置DMA的外设递增模式，一个外设

  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

  //设置DMA的内存递增模式

  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

  //外设数据字长

  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

  //内存数据字长

  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

  //设置DMA的传输模式

  //DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;

  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

  //设置DMA的优先级别

  DMA_InitStructure.DMA_Priority = DMA_Priority_High;

  //设置DMA的2个memory中的变量互相访问

  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

  DMA_Init( DMA1_Channel3, &DMA_InitStructure );

  //开启时钟

  RCC_APB2PeriphClockCmd( RCC_APB2Periph_TIM1, ENABLE );

  //重新将Timer设置为缺省值

  TIM_DeInit( TIM1 );

  //采用内部时钟提供时钟源

  TIM_InternalClockConfig( TIM1 );

  //预分频

  timInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;

  //计数频率为500ns跳转1次

  timInitStruct.TIM_Prescaler = SystemCoreClock /  - ;

  //向上计数

  timInitStruct.TIM_CounterMode = TIM_CounterMode_Up;

  timInitStruct.TIM_RepetitionCounter = ;

  //这个值实际上就是TIMX->ARR，延时开始时重新设定即可

  timInitStruct.TIM_Period = 0xffff;

  //初始化定时器

  TIM_TimeBaseInit( TIM1, &timInitStruct );

  //输入捕获配置

  //选择通道

  tim_icinit.TIM_Channel = TIM_Channel_1;

  //硬件滤波

  tim_icinit.TIM_ICFilter = 0x0;

  //触发捕获的电平

  tim_icinit.TIM_ICPolarity = TIM_ICPolarity_Falling;

  //每次检测到触发电平都捕获

  tim_icinit.TIM_ICPrescaler = TIM_ICPSC_DIV1;

  //通道方向选择

  tim_icinit.TIM_ICSelection = TIM_ICSelection_DirectTI;

  //初始化

  //TIM_ICInit(TIM1,&tim_icinit);

  TIM_PWMIConfig( TIM1, &tim_icinit );

  //禁止ARR预装载缓冲器

  //TIM_ARRPreloadConfig(TIM1, DISABLE);  

  //输入跳变选择

  TIM_SelectInputTrigger( TIM1, TIM_TS_TI1FP1 );

  //从机模式:复位模式

  TIM_SelectSlaveMode( TIM1, TIM_SlaveMode_Reset );

  //主从模式选择

  TIM_SelectMasterSlaveMode( TIM1, TIM_MasterSlaveMode_Enable );

  //配置定时器的DMA

  TIM_DMAConfig( TIM1, TIM_DMABase_CCR1, TIM_DMABurstLength_2Bytes );

  //产生DMA请求信号

  TIM_DMACmd( TIM1, TIM_DMA_CC1, ENABLE );

  //配置定时器的DMA

  TIM_DMAConfig( TIM1, TIM_DMABase_CCR2, TIM_DMABurstLength_2Bytes );

  //产生DMA请求信号

  TIM_DMACmd( TIM1, TIM_DMA_CC2, ENABLE );

  //打开定时器

  TIM_Cmd( TIM1, ENABLE );

}

/*********************************************************************

 *             接口函数:打开定时器

 *参数:state:状态:0:关闭,1:打开

 **********************************************************************/

void inf_infrared_study_open_timer( uint8_t state )

{

  if ( state )

  {

    TIM_Cmd( TIM1, ENABLE );

  }

  else

  {

    TIM_Cmd( TIM1, DISABLE );

  }

}

/*********************************************************************

 *             接口函数:打开中断

 *参数:state:状态:0:关闭,1:打开

 **********************************************************************/

void inf_infrared_study_open_irq( uint8_t state )

{

  //定义中断结构体

  NVIC_InitTypeDef NVIC_InitStructure;

  if ( state )

  {

    //打开中断

    NVIC_InitStructure.NVIC_IRQChannel = EXTI1_IRQn;        //通道设置为外部中断线

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = ;     //中断抢占先等级

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = ;            //中断响应优先级

    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;               //打开中断

    NVIC_Init( &NVIC_InitStructure );                                 //初始化

  }

  else

  {

    //关闭中断

    NVIC_InitStructure.NVIC_IRQChannel = EXTI1_IRQn;        //通道设置为外部中断线

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = ;     //中断抢占先等级

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = ;            //中断响应优先级

    NVIC_InitStructure.NVIC_IRQChannelCmd = DISABLE;              //打开中断

    NVIC_Init( &NVIC_InitStructure );                                 //初始化

  }

}

/*********************************************************************

 *             接口函数:打开DMA

 *参数:state:状态:0:关闭,1:打开

 **********************************************************************/

void inf_infrared_study_open_dma( uint8_t state )

{

  if ( state )

  {

    //设置传输数据长度

    //DMA_SetCurrDataCounter(DMA1_Channel3,RX_LEN_TIM_DMA);

    //打开DMA

    DMA_Cmd( DMA1_Channel2, ENABLE );

    DMA_Cmd( DMA1_Channel3, ENABLE );

  }

  else

  {

    DMA_Cmd( DMA1_Channel2, DISABLE );

    DMA_Cmd( DMA1_Channel3, ENABLE );

  }

}

/*********************************************************************

 *             接口函数:得到DMA接收帧长

 *返回:帧长

 **********************************************************************/

uint16_t inf_infrared_study_dma_rx_len( void )

{

  //获得接收帧帧长

  return ( RX_LEN_TIM_DMA - DMA_GetCurrDataCounter( DMA1_Channel2 ) );

}