高精度测频率

一.捕获法

现给出主要代码CaiJi.c

#include "stm32f10x.h"

#include "CaiJi.h"

//配置系统时钟,使能各外设时钟

void RCC_Configuration(void)

{

SystemInit();

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //时钟配置

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOF | RCC_APB2Periph_AFIO , ENABLE );

}

void GPIO_Configuration(void)

{

GPIO_InitTypeDef GPIO_InitStructure;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOF, &GPIO_InitStructure);

GPIO_SetBits(GPIOF,GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

GPIO_Init(GPIOA, &GPIO_InitStructure);

}

void NVIC_Configuration(void)

{

NVIC_InitTypeDef NVIC_InitStructure;

#ifdef VECT_TAB_RAM

NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);

#else

NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);

#endif

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //NVIC配置

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

}

//////////////////////////////////////////////////////////////////////////

void TIM3_Configuration(void)//TIM2初始化函数

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

TIM_ICInitTypeDef TIM_ICInitStructure;

TIM_DeInit(TIM3);

TIM_TimeBaseStructure.TIM_Period = 0xffff;

TIM_TimeBaseStructure.TIM_Prescaler = ?; //此值保密，呵呵，大家自己可以算一下，唯一奥，不然不准

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

TIM_ICInitStructure.TIM_Channel = TIM_Channel_2; //通道选择

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿触发

TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;//管脚与寄存器对

应关系

TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;

//输入预分频。意思是控制在多少个输入周期做一次捕获，如果

//输入的信号频率没有变，测得的周期也不会变。比如选择4分频，则每四个输入周

//期才做一次捕获，这样在输入信号变化不频繁的情况下，可以减少软件被不断中断的次数。

TIM_ICInitStructure.TIM_ICFilter = 0x0; //滤波设置，经历几个周期跳变认定波形稳定0x0～0xF

TIM_ICInit(TIM3, &TIM_ICInitStructure);

//TIM_PWMIConfig(TIM3, &TIM_ICInitStructure); //根据参数配置TIM外设信息

TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2); //选择IC2为始终触发源

TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);//TIM从模式：触发信号的上升沿重新初始化计数器和触发寄存器的更新事件

TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable); //启动定时器的被动触发

TIM_Cmd(TIM3, ENABLE); //启动TIM2