利用STM32的PWM輸入捕獲功能，可以測方波的占空比和(或)頻率

使用時(shí)將相應(yīng)的輸入配置為對應(yīng)定時(shí)器對應(yīng)的復(fù)用功能，外部待測量波形從該引腳輸入

再配置定時(shí)器輸入捕獲功能相應(yīng)參數(shù)，選擇主從模式，最后打開中斷或者DMA讀取測量數(shù)據(jù)

1. Enable TIM clock

2. Configure the TIM pins by configuring the corresponding GPIO pins

3. Fill the TIM_ICInitStruct

5. Call TIM_ICInit(TIMx, &TIM_ICInitStruct) ;. Call TIM_PWMIConfig(TIMx, &TIM_ICInitStruct) ;

6. Enable the NVIC or the DMA to read the measured frequency.

7. Enable the corresponding interrupt (or DMA request) to read the Captured value

8. Configure the slave mode controller in reset mode

9. Call the TIM_Cmd(ENABLE) function to enable the TIM counter.

10. Use TIM_GetCapturex(TIMx); to read the captured value.

代碼：

#ifndef __PWM_INPUT_H

#define __PWM_INPUT_H

#include "main.h"

#define PWM_INPUT_TIM TIM3

#define PWM_INPUT_TIM_CLK RCC_APB1Periph_TIM3

#define PWM_INPUT_CHANNEL TIM_Channel_2

#define PWM_INPUT_PIN GPIO_Pin_4

#define PWM_INPUT_PORT GPIOA

#define PWM_INPUT_GPIOCLK RCC_AHBPeriph_GPIOA

#define PWM_INPUT_GPIOAF GPIO_AF_2

#define PWM_INPUT_PINSOURCE GPIO_PinSource4

void PWM_INPUT_Config(void);

void TIM3_IRQHandler(void);

#endif

//========================================================/

#include "PWM_Input.h"

volatile uint16_t IC2Value = 0;

volatile uint16_t DutyCycle = 0;

volatile uint32_t Frequency = 0;

void PWM_INPUT_Config(void)

{

GPIO_InitTypeDef GPIO_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;

TIM_ICInitTypeDef TIM_ICInitStructure;

RCC_AHBPeriphClockCmd(PWM_INPUT_GPIOCLK,ENABLE);

RCC_APB1PeriphClockCmd(PWM_INPUT_TIM_CLK,ENABLE);

GPIO_InitStructure.GPIO_Pin = PWM_INPUT_PIN;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;

GPIO_Init(PWM_INPUT_PORT, &GPIO_InitStructure);

GPIO_PinAFConfig(PWM_INPUT_PORT, PWM_INPUT_PINSOURCE, PWM_INPUT_GPIOAF);

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

TIM_ICInitStructure.TIM_Channel=PWM_INPUT_CHANNEL;

TIM_ICInitStructure.TIM_ICFilter=0x0;

TIM_ICInitStructure.TIM_ICPolarity=TIM_ICPolarity_Rising;

TIM_ICInitStructure.TIM_ICPrescaler=TIM_ICPSC_DIV1;

TIM_ICInitStructure.TIM_ICSelection=TIM_ICSelection_DirectTI;

TIM_PWMIConfig(PWM_INPUT_TIM,&TIM_ICInitStructure);

TIM_SelectInputTrigger(PWM_INPUT_TIM,TIM_TS_TI2FP2);

TIM_SelectSlaveMode(PWM_INPUT_TIM,TIM_SlaveMode_Reset);

TIM_SelectMasterSlaveMode(PWM_INPUT_TIM,TIM_MasterSlaveMode_Enable);

TIM_Cmd(PWM_INPUT_TIM,ENABLE);

TIM_ITConfig(PWM_INPUT_TIM,TIM_IT_CC2,ENABLE);

}

void TIM3_IRQHandler(void)

{

TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);

IC2Value = TIM_GetCapture2(TIM3);

if (IC2Value != 0)

{

DutyCycle = (TIM_GetCapture1(TIM3) * 100) / IC2Value;

Frequency = 72000000 / IC2Value;

}

else

{

DutyCycle = 0;

Frequency = 0;

}

// printf("DutyCycle= %dn",DutyCycle);

// printf("Frequency= %dn",Frequency);

}