TIM2_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;这里的映射不太明白?

喝茶的宠物猪

stm32进行输入捕获实验，使用TIM2的CH1

TIM2_ICInitStructure.TIM_Channel = TIM_Channel_1; //CC1S=01         选择输入端 IC1映射到TI1上
TIM2_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;        //上升沿捕获
TIM2_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
TIM2_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;         //配置输入分频,不分频
TIM2_ICInitStructure.TIM_ICFilter = 0x00;//IC1F=0000 配置输入滤波器 不滤波
TIM_ICInit(TIM2, &TIM2_ICInitStructure);


这里为什么TIM2_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; 而不是配置到 TIM_ICSelection_IndirectTI上？