【蓝桥杯嵌入式】【STM32】10_InputCaputer之输入捕获

前言

  下载工程文件&＃xff1a;
  https://gitee.com/Joseph_Cooper/blue-bridge-embedded

1、输入捕获原理

1.1、设置输入捕获滤波器

  根据输入信号的特点&＃xff0c;配置输入滤波器为所需的带宽(即输入为TIx时&＃xff0c;输入滤波器控制位是TIMx_CCMRx寄存器中的ICxF位)。假设输入信号在最多5个内部时钟周期的时间内抖动&＃xff0c;我们须配置滤波器的带宽长于5个时钟周期&＃xff1b;因此我们可以(以fDTS频率)连续采样8次&＃xff0c;以确认在TI1上一次真实的边沿变换&＃xff0c;即在TIMx_CCMR1寄存器中写入IC1F&＃61;0011。

1.2、设置输入捕获的极性

  改变CC1P位的值以改变上升沿触发或是下降沿触发。可通过库函数void TIM_OC1PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity)来设置。

1.3、设置输入捕获的映射通道

  通道内获得的信号是可以通过设置交给不同的IC来进行处理的&＃xff0c;比如&＃xff0c;我们可以将通道1捕获的信号送给IC2处理。

1.4、设置输入捕获分频器

  可设置多次上升沿触发一次捕获也就是相当于分频的作用。

1.5、捕获到有效信号可开启中断

  捕获到一次信号可以进入相应的中断服务函数。

1.6、捕获实现频率和占空比的获取

1、设置为上升沿捕获、定时器值清零
2、上升沿捕获成功后记录定时器中的值A再设置为下降沿捕获
3、下降沿捕获成功后记录定时器中的值B再次设置为上升沿捕获。
4、再次设置为上升沿捕获&＃xff0c;捕获成功后记录定时器中的值C&＃xff0c;清空定时器计数值&＃xff0c;(C−A)⋅1fTIM(C-A)\cdot\frac1{f_{TIM}}(C−A)⋅fTIM​1​即为该波形的周期&＃xff0c;其倒数即是频率&＃xff0c;B−AC−A×100%\frac {B-A}{C-A}\times100\%C−AB−A​×100%即为占空比。

2、输入捕获功能配置流程

1、初始化定时器和通道对应IO的时钟。
2、初始化IO口&＃xff0c;模式为输入
  GPIO_Init();
  GPIO_InitStructure.GPIO_Mode &＃61; GPIO_Mode_IPD; //PA0 输入
3、初始化定时器ARR&＃xff0c;PSC
   TIM_TimeBaseInit();
4、初始化输入捕获通道
  TIM_ICInit();
5、使能定时器
  TIM_Cmd();
6、如果要开启捕获中断
  TIM_ITConfig();
  NVIC_Init();
7、编写中断服务函数
  TIMx_IRQHandler();

需要用到的函数&＃xff1a;
  通道极性设置函数
  void TIM_OCxPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity)&＃xff1b;
  获取捕获值
  uint32_t TIM_GetCapture1(TIM_TypeDef* TIMx)&＃xff1b;

3、部分源码

PWM输出&＃xff1a;

输入捕获&＃xff1a;

main.c:

#include "Headfile.h"/**
* &＃64;file main.c
* &＃64;brief 实现PA1捕获PA9、PA10端的输出,显示频率和占空比
* &＃64;version 1.0
* &＃64;author JosephCooper
* &＃64;date 2020.10.09
*//** 滴答定时器实现延时中间变量 */
u32 TimingDelay &＃61; 0;
extern __IO uint32_t TIM2Freq;
extern u8 TIM2FreqReady;
extern __IO uint32_t TIM2Duty;void Delay_Ms(u32 nTime);//Main Body
int main(void)
{uint32_t i &＃61; 0;u8 Str[200];uint32_t TIM2Freq_BP &＃61; 0;uint32_t TIM2Duty_BP &＃61; 0;memset(Str,0x00,sizeof(Str));//清空数组SysTick_Config(SystemCoreClock/1000);NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);Delay_Ms(200);LEDInit();//LED初始化//关闭所有LEDLEDCmd(Bit_SET);GPIO_Write(GPIOC,GPIO_ReadOutputData(GPIOC) | 0xFF00);LEDCmd(Bit_RESET);STM3210B_LCD_Init();LCD_Clear(Blue);LCD_SetBackColor(Blue);LCD_SetTextColor(White);BuzzerInit();//蜂鸣器初始化TIM2_ICInit();TIM1_PWMInit();//TIM1_PWM初始化while(1){if(TIM2FreqReady){TIM2FreqReady &＃61; 0;if( (TIM2Freq!&＃61;TIM2Freq_BP) || (TIM2Duty!&＃61;TIM2Duty_BP) ){TIM2Freq_BP &＃61; TIM2Duty;TIM2Duty_BP &＃61; TIM2Freq;sprintf((char*)Str,"TIM2Freq:%dHz ", TIM2Freq);LCD_DisplayStringLine(Line2,Str);sprintf((char*)Str,"TIM2Duty:%d%% ", TIM2Duty);LCD_DisplayStringLine(Line3,Str);for(i&＃61;0; i<500000; i&＃43;&＃43;);//刷新延迟}}}
}//
void Delay_Ms(u32 nTime)
{TimingDelay &＃61; nTime;while(TimingDelay !&＃61; 0);
}

stm32f10x_it.c:

#include "stm32f10x_tim.h"
#include "stm32f10x.h"
extern u32 TimingDelay;
...
//7、编写中断服务函数
__IO uint16_t IC2ReadValue1 &＃61; 0, IC2ReadValue2 &＃61; 0,IC2ReadValue_LOW &＃61; 0;
__IO uint16_t CaptureNumber &＃61; 0;
__IO uint32_t Capture &＃61; 0;
__IO uint32_t TIM2Freq &＃61; 0;
__IO uint32_t TIM2Duty &＃61; 0;
u8 TIM2FreqReady &＃61; 0;
void TIM2_IRQHandler(void)
{ if(TIM_GetITStatus(TIM2, TIM_IT_CC2) &＃61;&＃61; SET) {/* Clear TIM3 Capture compare interrupt pending bit */TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);if(CaptureNumber &＃61;&＃61; 0){/* Get the Input Capture value */IC2ReadValue1 &＃61; TIM_GetCapture2(TIM2);CaptureNumber &＃61; 1;//设置下降沿捕获TIM_OC2PolarityConfig(TIM2,TIM_OCPolarity_Low);}else if(CaptureNumber &＃61;&＃61; 1){IC2ReadValue_LOW &＃61; TIM_GetCapture2(TIM2);CaptureNumber &＃61; 2;//设置上升沿捕获TIM_OC2PolarityConfig(TIM2,TIM_OCPolarity_High);}else if(CaptureNumber &＃61;&＃61; 2){/* Get the Input Capture value */IC2ReadValue2 &＃61; TIM_GetCapture2(TIM2); /* Capture computation */if (IC2ReadValue2 > IC2ReadValue1){Capture &＃61; (IC2ReadValue2 - IC2ReadValue1); }else{Capture &＃61; ((0xFFFF - IC2ReadValue1) &＃43; IC2ReadValue2);}/* Frequency computation */ TIM2Duty &＃61; ( (IC2ReadValue_LOW-IC2ReadValue1)*100 ) / Capture;TIM2Freq &＃61; 1000000 / Capture;//定时器经过72分频后的频率CaptureNumber &＃61; 0;TIM2FreqReady &＃61; 1;TIM_SetCounter(TIM2,0);}}
}


InputCaputer.c

#include "Headfile.h"void TIM2_ICInit()
{TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;TIM_ICInitTypeDef TIM2_ICInitStructure;GPIO_InitTypeDef GPIO_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;//1、初始化定时器和通道对应IO的时钟。RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);//2、初始化PA1&＃xff0c;模式为输入GPIO_InitStructure.GPIO_Pin &＃61; GPIO_Pin_1;GPIO_InitStructure.GPIO_Speed &＃61; GPIO_Speed_50MHz;GPIO_InitStructure.GPIO_Mode &＃61; GPIO_Mode_IN_FLOATING;//浮空输入GPIO_Init(GPIOA, &GPIO_InitStructure);//3、初始化定时器&＃xff08;时基设置&＃xff09;TIM_TimeBaseStructure.TIM_Prescaler &＃61; 72 - 1 ;TIM_TimeBaseStructure.TIM_CounterMode &＃61; TIM_CounterMode_Up;TIM_TimeBaseStructure.TIM_Period &＃61; 0xFFFF;TIM_TimeBaseStructure.TIM_ClockDivision &＃61; 0;TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);//4、初始化输入捕获通道TIM2_ICInitStructure.TIM_Channel &＃61; TIM_Channel_2;//定时器2的通道2TIM2_ICInitStructure.TIM_ICPolarity &＃61; TIM_ICPolarity_Rising;//上升沿捕获TIM2_ICInitStructure.TIM_ICSelection &＃61; TIM_ICSelection_DirectTI;//使用通道默认IC即IC2TIM2_ICInitStructure.TIM_ICPrescaler &＃61; TIM_ICPSC_DIV1;//不分频TIM2_ICInitStructure.TIM_ICFilter &＃61; 0x00;//不滤波//5、使能定时器TIM_ICInit(TIM2, &TIM2_ICInitStructure);//IC初始化TIM_Cmd(TIM2, ENABLE);//打开定时器//6、如果要开启捕获中断NVIC_InitStructure.NVIC_IRQChannel &＃61; TIM2_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority &＃61; 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority &＃61; 1;NVIC_InitStructure.NVIC_IRQChannelCmd &＃61; ENABLE;NVIC_Init(&NVIC_InitStructure);TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);
}


  关于LCD刷新的问题&＃xff1a;LCD在刷新时可能因为中断打断出现乱码的问题&＃xff0c;将要显示的字符串添加&＃xff08;用空格补全&＃xff09;至总长度超过20位即可sprintf((char*)Str,"TIM2Freq:%dHz ", TIM2Freq);
。