STM32捕获周期问题

王晨

不明白“ IC1的捕获寄存器捕获PWM的高电平周期”这句话在哪个里面体现了？ 我只配置了通道2的输入捕获功能呀，为什么 通道1TIM_GetCapture1(TIM2)捕获了？

1. /* TIM2 configuration: PWM Input mode ------------------------
   
2.      The external signal is connected to TIM2 CH2 pin (PA.01),
   
3.      The Rising edge is used as active edge,
   
4.      The TIM2 CCR2 is used to compute the frequency value
   
5.      The TIM2 CCR1 is used to compute the duty cycle value
   
6.   ------------------------------------------------------------ */
   
7. 
   
8.   TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
   
9.   TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
   
10.   TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
    
11.   TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    
12.   TIM_ICInitStructure.TIM_ICFilter = 0x0;
    
13. 
    
14.   TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);
    
15. 
    
16.   /* Select the TIM2 Input Trigger: TI2FP2 */
    
17.   TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2);
    
18. 
    
19.   /* Select the slave Mode: Reset Mode */
    
20.   TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);
    
21. 
    
22.   /* Enable the Master/Slave Mode */
    
23.   TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable);
    
24. 
    
25.   /* TIM enable counter */
    
26.   TIM_Cmd(TIM2, ENABLE);
    
27. 
    
28.   /* Enable the CC2 Interrupt Request */
    
29.   TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);

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1. void TIM2_IRQHandler(void)
   
2. {
   
3.   /* Clear TIM2 Capture compare interrupt pending bit */
   
4.   TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
   
5. 
   
6.   /* Get the Input Capture value */
   
7.   IC2Value = TIM_GetCapture2(TIM2);
   
8. 
   
9.   if (IC2Value != 0)
   
10.   {
    
11.     /* Duty cycle computation */
    
12.     DutyCycle = (TIM_GetCapture1(TIM2) * 100) / IC2Value;
    
13. 
    
14.     /* Frequency computation */
    
15.     Frequency = 72000000 / IC2Value;
    
16.   }
    
17.   else
    
18.   {
    
19.     DutyCycle = 0;
    
20.     Frequency = 0;
    
21.   }
    
22. }

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王晨

TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
这个是用来映射管脚跟寄存器的吗？ 文档上面说 每个定时器有四个输入捕获通道IC1、IC2、IC3、IC4。且IC1 IC2一组，IC3 IC4一组。并且可是设置管脚和寄存器的对应关系