ADC触发电平研究

hanhan0519

/* TIM1 configuration ------------------------------------------------------*/
  /* Time Base configuration */
  TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
  TIM_TimeBaseStructure.TIM_Period = 0xFF;         
  TIM_TimeBaseStructure.TIM_Prescaler = 0x4;      
  TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;   
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; 
  TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
  /* TIM1 channel1 configuration in PWM mode */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;               
  TIM_OCInitStructure.TIM_Pulse = 0x7F;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;        
  ITM_OC1Init(TIM1, &TIM_OCInitStructure);

  /* DMA1 Channel1 Configuration ----------------------------------------------*/
  DMA_DeInit(DMA1_Channel1);
  DMA_InitStructure.DMA_PeripheralBaseAddr = ADC1_DR_Address;
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)ADC_RegularConvertedValueTab;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
  DMA_InitStructure.DMA_BufferSize = 32;
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
  DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
  DMA_Init(DMA1_Channel1, &DMA_InitStructure);
 
  /* Enable DMA1 channel1 */
  DMA_Cmd(DMA1_Channel1, ENABLE);

  /* ADC1 configuration ------------------------------------------------------*/
  ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
  ADC_InitStructure.ADC_ScanConvMode = DISABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfChannel = 1;
  ADC_Init(ADC1, &ADC_InitStructure);

  /* ADC1 regular channel14 configuration */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_14, 1, ADC_SampleTime_13Cycles5);

  /* Set injected sequencer length */
  ADC_InjectedSequencerLengthConfig(ADC1, 1);
  /* ADC1 injected channel Configuration */
  ADC_InjectedChannelConfig(ADC1, ADC_Channel_11, 1, ADC_SampleTime_71Cycles5);
  /* ADC1 injected external trigger configuration */
  ADC_ExternalTrigInjectedConvConfig(ADC1, ADC_ExternalTrigInjecConv_None);

  /* Enable automatic injected conversion start after regular one */
  ADC_AutoInjectedConvCmd(ADC1, ENABLE);

  /* Enable ADC1 DMA */
  ADC_DMACmd(ADC1, ENABLE);

  /* Enable ADC1 external trigger */
  ADC_ExternalTrigConvCmd(ADC1, ENABLE);

  /* Enable JEOC interrupt */
  ADC_ITConfig(ADC1, ADC_IT_JEOC, ENABLE);

  /* Enable ADC1 */
  ADC_Cmd(ADC1, ENABLE);

  /* Enable ADC1 reset calibration register */  
  ADC_ResetCalibration(ADC1);
  /* Check the end of ADC1 reset calibration register */
  while(ADC_GetResetCalibrationStatus(ADC1));

  /* Start ADC1 calibration */
  ADC_StartCalibration(ADC1);
  /* Check the end of ADC1 calibration */
  while(ADC_GetCalibrationStatus(ADC1));

  /* TIM1 counter enable */
  TIM_Cmd(TIM1, ENABLE);
  /* TIM1 main Output Enable */
  TIM_CtrlPWMOutputs(TIM1, ENABLE); 

  /* Test on channel1 transfer complete flag */
  while(!DMA_GetFlagStatus(DMA1_FLAG_TC1));
  /* Clear channel1 transfer complete flag */
  DMA_ClearFlag(DMA1_FLAG_TC1);

  /* TIM1 counter disable */
  TIM_Cmd(TIM1, DISABLE);
这段程序是MDK软件提供的例子，我最近一直在研究受益匪浅，收获很大，但是有个问题有点疑惑。这个ADC程序，选择TIME1 OC1作为规则组触发，注入组为软件触发。设置如下：定时1装载值为OXFF,向上计数，分频系数为4，捕获值为OX7F,输出极性为LOW.问题：当定时器计数到7F时，是不是 输出低电平，没有达到的时候应该为高吧。如果是这样的话，那么什么时候规则组开始ADC转换，难道说刚开始计数器是0的时候。ADC手册上说当外部触发信号被选为ADC规则或注入转换时，只有它的上升沿可以启动转换。

正点原子

1,这个问题,你自己试验.
2,是上升沿启动,也就是说当你的OC1输出从0变为1的时候,就开始ADC转换.