以通用定时器TIM3产生脉冲信号，连接到高级定时器TIM1，捕获TIM1的PWM信号

PWM输入捕获只能使用通道1和通道2，因为触发从模式控制器的信号只有TI1和TI2的

#include "stm32f10x.h"


//PWM 输出模式  TIM2产生PWM信号    F=TIM_CLK/[(ARR+1)(PSC+1)]   令频率为1kHz，使得psc=71，arr=9

void TIM_Config()//Period=9   当Channel2Pulse=5，占空比为50%
{
	GPIO_InitTypeDef  GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
	TIM_OCInitTypeDef  TIM_OCInitStructure;	
	
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);	
    //PWM输出引脚初始化
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 ;	//PA1 PA2 - PWM_OutPut
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
			
	//时基结构体初始化
	TIM_TimeBaseStructure.TIM_Period = 9; 
	TIM_TimeBaseStructure.TIM_Prescaler = 71;
	TIM_TimeBaseStructure.TIM_ClockDivision = 0;
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
	//输出比较结构体初始化		
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
	TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
	TIM_OCInitStructure.TIM_Pulse = Channel2Pulse;
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
	TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
	TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
	TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;		
	TIM_OC2Init(TIM2, &TIM_OCInitStructure);

	TIM_Cmd(TIM2, ENABLE);
	TIM_CtrlPWMOutputs(TIM2, ENABLE);//使能TIM2 PWM输出模式
}
//令可以捕获的最小频率为1kHz，使得psc=71，arr=999。即，如果输出的频率小于1kHZ，即可捕获的最大周期为1us，就捕获不到了
void PMW_IN(void)//TIM3接收信号，CH2通道接收来自
{	
	GPIO_InitTypeDef  GPIO_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); 
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);	
    //输入引脚配置
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;//CH2通道
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;  //浮空输入 用以捕获方波
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA, &GPIO_InitStructure);
    //中断配置
	NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;           
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);	
	//时钟基础初始化
	TIM_TimeBaseStructure.TIM_Period = 999; 
	TIM_TimeBaseStructure.TIM_Prescaler = 71; 
	TIM_TimeBaseStructure.TIM_ClockDivision = 0; 
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; 
	TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
	//PWM输入基本配置	
	TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;  //选择通道2，对应输入引脚为PA7，
	TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;  
	TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;  //管脚和寄存器的对应关系
	TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;  //输入捕获不分频
	TIM_ICInitStructure.TIM_ICFilter = 0x0;  //不滤波 
	TIM_PWMIConfig(TIM3, &TIM_ICInitStructure);  //PWM输入配置
	
	TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2);  //选择TIMx输入捕获的触发信号，因为选择的是CH2通道，直连映射，所以是TI2FP2作为触发信号
	TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);  //选择从模式：复位模式
	//复位模式：上升沿重新初始化计数器，并且产生一个更新寄存器的信号
	//PWM输入模式时，从模式必须工作在复位模式，当捕获开始，计数器CNT复位
	TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable); 
	TIM_Cmd(TIM3, ENABLE);  //使能计数器
	TIM_ITConfig(TIM3, TIM_IT_CC2, ENABLE);  //允许捕获/比较2中断
}

中断服务函数

void TIM3_IRQHandler(void)
{
	TIM_ClearITPendingBit(TIM3, TIM_IT_Update);
	IC1Value=TIM_GetCapture1(TIM3);//占空比
	IC2Value=TIM_GetCapture2(TIM3);//周期
	if(IC2Value!=0)
	{
		Dutycle=(float)((IC1Value+1)/(IC2Value+1));//占空比
		frequency=(float)(72000000/1000/(IC2Value+1);//频率
	}
	else
	{
		Dutycle=0;
		frequency=0;
	}
}