STM32的定时器输入捕获-超声波测距案例

gitee代码

https://gitee.com/xiaolixi/l-stm32/tree/master/STM32F103C8T6/2-1tem-ld-timer-input-pluse

输入捕获硬件电路

案例说明

1. 使用超声波测距传感器
2. 使用tim1的输入捕获测量超声波传感器的返回值，其中Echo引脚使用通道1和通道2的间接选择，Trig使用PB0。距离小于1M点亮LED，LED灯使用PA1

主函数代码

其他代码见仓库

#include "stm32f10x.h"
#include "LED.h"
#include "app_timer.h"
#include "Delay.h"
#include "math.h"
 
#define TRIG GPIOB

/**
Echo 		PA8
Trigger PB0
LED 		PA1
*/
void GPIOB_0_init() {
		// Trigger引脚
		RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
	
		GPIO_InitTypeDef GPIO_InitStruct;
		GPIO_InitStruct.GPIO_Mode = GPIO_Mode_Out_PP;
		GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0;
		GPIO_InitStruct.GPIO_Speed = GPIO_Speed_10MHz;
		GPIO_Init(TRIG, &GPIO_InitStruct);
}

void timer_init(void) {
		RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
	
	
		TIM_TimeBaseInitTypeDef TIM_TIM_TimeBaseInitStruct;
		TIM_TIM_TimeBaseInitStruct.TIM_RepetitionCounter = 0;
		TIM_TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;
		TIM_TIM_TimeBaseInitStruct.TIM_Period = 65535;
		TIM_TIM_TimeBaseInitStruct.TIM_Prescaler = 71;
		TIM_TimeBaseInit(TIM1, &TIM_TIM_TimeBaseInitStruct);
	
	
		// Echo 引脚
		RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
	
		GPIO_InitTypeDef GPIO_InitStruct;
		GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IPD;
		GPIO_InitStruct.GPIO_Pin = GPIO_Pin_8;
		GPIO_Init(GPIOA, &GPIO_InitStruct);
	
		TIM_ICInitTypeDef TIM_ICInitStruct;
		TIM_ICInitStruct.TIM_Channel = TIM_Channel_1;
		TIM_ICInitStruct.TIM_ICFilter = 0;
		TIM_ICInitStruct.TIM_ICPolarity = TIM_ICPolarity_Rising;
		TIM_ICInitStruct.TIM_ICPrescaler = TIM_ICPSC_DIV1;
		TIM_ICInitStruct.TIM_ICSelection = TIM_ICSelection_DirectTI;
	
		TIM_ICInit(TIM1, &TIM_ICInitStruct);
		
		
		TIM_ICInitStruct.TIM_Channel = TIM_Channel_2;
		TIM_ICInitStruct.TIM_ICFilter = 0;
		TIM_ICInitStruct.TIM_ICPolarity = TIM_ICPolarity_Falling;
		TIM_ICInitStruct.TIM_ICPrescaler = TIM_ICPSC_DIV1;
		TIM_ICInitStruct.TIM_ICSelection = TIM_ICSelection_IndirectTI; // 间接选择
	
		TIM_ICInit(TIM1, &TIM_ICInitStruct);
}


int main(void)
{
	GPIOB_0_init();
	// LED 显示
	LED_Init();
	LED1_OFF();
	
	timer_init();
	
	while(1) {
		TIM_SetCounter(TIM1, 0);
		
		TIM_ClearFlag(TIM1, TIM_FLAG_CC1);
		TIM_ClearFlag(TIM1, TIM_FLAG_CC2);
		
		TIM_Cmd(TIM1, ENABLE);
		
		GPIO_WriteBit(TRIG, GPIO_Pin_0, Bit_SET);
		Delay_us(20);
		GPIO_WriteBit(TRIG, GPIO_Pin_0, Bit_RESET);
		
		while(TIM_GetFlagStatus(TIM1, TIM_FLAG_CC1) == RESET) {
			;
		}
		
		while(TIM_GetFlagStatus(TIM1, TIM_FLAG_CC2) == RESET) {
			;
		}
		
		TIM_Cmd(TIM1, DISABLE);
		
		// 换算
		float distance = (TIM_GetCapture2(TIM1) - TIM_GetCapture1(TIM1)) * 1e-6 * 340.0f / 2;
		
		if (distance < 1.0) {
				LED1_ON();
		} else {
				LED1_OFF();
		}
		Delay_ms(100);
	}
}