等精度测量法:定时器1对被测信号计数65536个周期作为闸门时间，在这个闸门时间内定时器2对标准信号进行计数。假定在这个闸门时间内标准信号的计数值为M。则有：65536/fc=M/fb通过这个公式就可以算出被测信号：fc=65536*fb/M。
本程序利用定时器3产生30KHZ的被测信号。定时器1对被测信号进行65536个周期计数。
定时器4产生60KHZ的标准信号。定时器2对标准信号在定时器1产生的闸门时间内计数。
主程序如下：
/**
******************************************************************************
* @file app.c
* @author wangfei
* @date 13-April-2012
* @e-mail wfmjj@hotmail.com
* @brief Initialize peripherals.
*****************************************************************************/
/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"
#include "app.h"
#include "bsp.h"
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
extern uint8_t TimeFlag;
extern uint32_t n_Counter;
uint16_t Counterh,Counterl;
uint8_t Data[5];
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*//**
* @brief This function handles NMI exception.
* @param None
* @retval None
*/
int main(void)
{
GPIO_ResetBits(GPIOE,(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3)); //可以通过观察LED口高电平时间
Bsp_Init();
while(1)
{
uint8_t i;
TIM_ITConfig(TIM1,TIM_IT_Trigger,ENABLE); //允许定时器1的触发中断
GPIO_SetBits(GPIOE,(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3));
TIM_Cmd(TIM1,ENABLE); //打开定时器1,当检测到TIM1_CH1通道的上升沿后立即触发中断
while(TimeFlag==0); //等待定时器1溢出中断
TIM1->DIER&=0X0000; //失能定时器1的所有中断
GPIO_ResetBits(GPIOE,(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3)); //可以通过观察LED口高电平时间
TimeFlag=0; //定时器1溢出标志置0
Counterh=n_Counter>>16; //得到32位数据中的高16位
Counterl=n_Counter; //得到32位数据中的低16位
Data[0]=Counterh>>8;
Data[1]=Counterh;
Data[2]=Counterl>>8;
Data[3]=Counterl;
for(i=0;i<4;i++)
{
USART_SendData(USART3,Data);
while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET);
}
Delay(100000000);
}
}
/**
* @brief Delay Function.
* @param nCount:specifies the Delay time length.
* @retval None
*/
void Delay(__IO uint32_t nCount)
{
while(nCount--)
{
}
}
外设初始化程序如下：
/**
******************************************************************************
* @file bsp.c
* @author wangfei
* @date 13-April-2012
* @e-mail wfmjj@hotmail.com
* @brief Initialize peripherals.
*****************************************************************************/
/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"
#include "bsp.h"/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*//**
* @brief This function handles NMI exception.
* @param None
* @retval None
*/
void Bsp_Init(void)
{
Bsp_GPIO_Config(); //对用到的外设IO口进行设置
Bsp_TIM1_Config(); //对被测信号进行计数
Bsp_TIM2_Config(); //对标准信号进行计数
Bsp_TIM3_Config(); //产生被测信号
Bsp_TIM4_Config(); //产生标准信号
Bsp_NVIC_Config(); //配置本程序中使用的中断
Bsp_USART3_Config(); //将标准信号的测量数值传送给PC机
}
/**
* @brief This function config GPIO.
* @param None
* @retval None
*/
void Bsp_GPIO_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE,ENABLE); //打开外设GPIOE的时钟
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC,ENABLE); //turn on gpioc clock
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE); //turn on GPIOA clock
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB,ENABLE); //打开GPIOB口的时钟TIM4_CH1--PB6
GPIO_InitStructure.GPIO_Pin=(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3); //led口配置
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType=GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_NOPULL;
GPIO_Init(GPIOE, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOC,GPIO_PinSource10,GPIO_AF_USART3); //Connect USART3 pins to AF7
GPIO_PinAFConfig(GPIOC,GPIO_PinSource11,GPIO_AF_USART3);
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_10 | GPIO_Pin_11;
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(GPIOC, &GPIO_InitStructure);
//Connect TIM3 Pin to AF2
GPIO_PinAFConfig(GPIOC,GPIO_PinSource6,GPIO_AF_TIM3); //TIM3_Ch1
GPIO_PinAFConfig(GPIOC,GPIO_PinSource7,GPIO_AF_TIM3); //TIM3_Ch2
GPIO_PinAFConfig(GPIOC,GPIO_PinSource8,GPIO_AF_TIM3); //TIM3_Ch3
GPIO_PinAFConfig(GPIOC,GPIO_PinSource9,GPIO_AF_TIM3); //TIM3_Ch4
// Config TIM3 Pin
GPIO_InitStructure.GPIO_Pin=(GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_9);
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(GPIOC, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_TIM1); //PA9--TIM1_CH2
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_9;
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(GPIOA, &GPIO_InitStructure);
//配置TIM2_CH1通道PA0引脚
GPIO_PinAFConfig(GPIOA,GPIO_PinSource0,GPIO_AF_TIM2); //PA0--TIM2_CH1
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_0;
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(GPIOA, &GPIO_InitStructure);
//配置TIM4_CHx通道
GPIO_PinAFConfig(GPIOB,GPIO_PinSource6,GPIO_AF_TIM4); //connect TIM4_CH1 to AF2
GPIO_PinAFConfig(GPIOB,GPIO_PinSource7,GPIO_AF_TIM4); //connect TIM4_CH2 to AF2
GPIO_PinAFConfig(GPIOB,GPIO_PinSource8,GPIO_AF_TIM4); //connect TIM4_CH3 to AF2
GPIO_PinAFConfig(GPIOB,GPIO_PinSource9,GPIO_AF_TIM4); //connect TIM4_CH4 to AF2
GPIO_InitStructure.GPIO_Pin =(GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_9);
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(GPIOB, &GPIO_InitStructure);
}
/**
* @brief This function config timer1.
* @param None
* @retval None
*/
void Bsp_TIM1_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1,ENABLE); //turn on timer1 clock
TIM_DeInit(TIM1);
TIM_TimeBaseStructure.TIM_Prescaler=0;
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //定时器1向上计数
TIM_TimeBaseStructure.TIM_Period=0xffff;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
TIM1->CCMR1|=0X0100; //配置定时器1为外部时钟模式1
TIM1->CCER&=0XFF5F;
TIM1->SMCR|=0X0067;
TIM_ClearFlag(TIM1,(TIM_FLAG_Update|TIM_FLAG_Trigger));
}
/**
* @brief This function config timer3.
* @param None
* @retval None
*/
void Bsp_TIM3_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //Open TIM3 Clock
TIM_TimeBaseStructure.TIM_Prescaler=3; //clk_cnt prescale
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //TIM3 Count mode
TIM_TimeBaseStructure.TIM_Period=699; //Fout_clk=Fclk_cnt/(ARR+1)=21000000/700=30KHZ
TIM_TimeBaseStructure.TIM_ClockDivision=0;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
/* PWM1 Mode configuration: TIM3_Ch1 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc1 as output
TIM_OCInitStructure.TIM_Pulse=350; //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc1 high level avaliable
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable); // turn on oc1 preload
/* PWM1 Mode configuration: TIM3_Ch2 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc2 as output
TIM_OCInitStructure.TIM_Pulse=200; //config TIM3_CCR2 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc2 high level avaliable
TIM_OC2Init(TIM3, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); // turn on oc2 preload
/* PWM1 Mode configuration: TIM3_CH3 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc3 as output
TIM_OCInitStructure.TIM_Pulse=100; //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc3 high level avaliable
TIM_OC3Init(TIM3, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable); // turn on oc3 preload
/* PWM1 Mode configuration: TIM3_CH4 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc4 as output
TIM_OCInitStructure.TIM_Pulse=500; //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc4 high level avaliable
TIM_OC4Init(TIM3, &TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable); // turn on oc4 preload
TIM_ARRPreloadConfig(TIM3, ENABLE); /* TIM3 enable counter */
TIM_Cmd(TIM3, ENABLE);
}
/**
* @brief This function config usart3.
* @param None
* @retval None
*/
void Bsp_USART3_Config(void)
{
USART_InitTypeDef USART_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE); //turn on usart3 clock
USART_InitStructure.USART_BaudRate =115200 ; //波特率设置
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART3, &USART_InitStructure);
//USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);
USART_Cmd(USART3,ENABLE);
USART_ClearFlag(USART3, USART_FLAG_TC); //清除发送完成标志位
}
/**
* @brief This function config nvic.
* @param None
* @retval None
*/
void Bsp_NVIC_Config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
NVIC_InitStructure.NVIC_IRQChannel=TIM1_TRG_COM_TIM11_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_InitStructure.NVIC_IRQChannel=TIM1_UP_TIM10_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
/**
* @brief This function config timer2.
* @param None
* @retval None
*/
void Bsp_TIM2_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE); //打开定时器2的时钟
TIM_DeInit(TIM2);
TIM_TimeBaseStructure.TIM_Prescaler=0;
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //定时器2向上计数
TIM_TimeBaseStructure.TIM_Period=0xffff;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM2->ARR|=0XFFFFFFFF; //配置
//定时器2外部时钟模式1的配置
TIM2->CCMR1|=0X0001;
TIM2->CCER&=0XFFF5;
TIM2->SMCR|=0X0057;
TIM_ClearFlag(TIM2,TIM_FLAG_Update); //初始化时必须将溢出中断清0必须在开溢出中断之前。
}
/**
* @brief This function config timer4.
* @param None
* @retval None
*/
void Bsp_TIM4_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE); //turn on TIM4 clock TIM_TimeBaseStructure.TIM_Prescaler=1; //Fck_cnt=84MHZ/2=42MHZ
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //TIM3 Count mode
TIM_TimeBaseStructure.TIM_Period=699; //Fout_clk=Fclk_cnt/(ARR+1)=42000/700=60KHZ
TIM_TimeBaseStructure.TIM_ClockDivision=0;
TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
/* PWM1 Mode configuration: TIM4_Ch1 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc1 as output
TIM_OCInitStructure.TIM_Pulse=350; //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc1 high level avaliable
TIM_OC1Init(TIM4, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable); // turn on oc1 preload
/* PWM1 Mode configuration: TIM4_Ch2 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc2 as output
TIM_OCInitStructure.TIM_Pulse=500; //config TIM3_CCR2 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc2 high level avaliable
TIM_OC2Init(TIM4, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable); // turn on oc2 preload
/* PWM1 Mode configuration: TIM4_CH3 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc3 as output
TIM_OCInitStructure.TIM_Pulse=100; //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc3 high level avaliable
TIM_OC3Init(TIM4, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable); // turn on oc3 preload
/* PWM1 Mode configuration: TIM4_CH4 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc4 as output
TIM_OCInitStructure.TIM_Pulse=600; //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //config oc4 high level avaliable
TIM_OC4Init(TIM4, &TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable); // turn on oc4 preload
TIM_ARRPreloadConfig(TIM4, ENABLE); /* TIM3 enable counter */
TIM_Cmd(TIM4, ENABLE);
}
定时器1触发中断程序如下：
void TIM1_TRG_COM_TIM11_IRQHandler(void)
{
if(TIM_GetITStatus(TIM1,TIM_IT_Trigger)==SET) //检查是否为触发中断
{
TIM1->DIER&=0XFFBF; //清除定时器1的触发中断
TIM1->DIER|=0X0001; //使能定时器1的溢出中断
TIM2->CR1|=0X0001; //打开定时器2使其对标准信号开始计数
TIM1->SR&=0XFFBF; //在退出中断之前必须清除其中断标志位
}
}
定时器1溢出中断如下：
void TIM1_UP_TIM10_IRQHandler(void)
{
if(TIM_GetITStatus(TIM1,TIM_IT_Update)==SET) //检查定时器1溢出标志位是否置1
{
n_Counter=TIM2->CNT; //读出计数器2的值
TIM1->CR1&=0XFFFE; //关闭定时器1
TIM2->CR1&=0XFFFE; //关闭定时器2
TIM2->CNT&=0X0000; //清除计数器2计数寄存器的值
TimeFlag=1; //1s标志位置1
TIM1->SR&=0XFFFE; //退出定时器1溢出中断之前,必须清除定时器1的溢出标志位
}
}
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