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#include "Ultrasonic.h"
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#include "stm32f10x.h"
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#include "delay.h"
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#define SoundSpeed 340 // <EFBFBD><EFBFBD><EFBFBD><EFBFBD> <EFBFBD><EFBFBD>λΪm/s
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void UltrasonicInit(void)
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{
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GPIO_InitTypeDef GPIO_InitStructure;
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TIM_TimeBaseInitTypeDef TIM3_TimeBase;
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RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE );
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RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
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//PA6--Trig
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GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
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GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
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GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
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GPIO_Init(GPIOA, &GPIO_InitStructure);
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//TIM3_CH2--PA7--Echo
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GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
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GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
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GPIO_Init(GPIOA, &GPIO_InitStructure);
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//<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ1MHz
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TIM3_TimeBase.TIM_ClockDivision = 0;
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TIM3_TimeBase.TIM_CounterMode = TIM_CounterMode_Up;
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TIM3_TimeBase.TIM_Period = 8999;
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TIM3_TimeBase.TIM_Prescaler = 72-1;
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TIM3_TimeBase.TIM_RepetitionCounter=0;
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TIM_TimeBaseInit(TIM3, &TIM3_TimeBase);
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}
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float UltrasonicDetect(void)
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{
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float time_s = 0;
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int i;
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float p[5];
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for(i=0;i<5;i++)
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{
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//<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>10us<EFBFBD>ĸߵ<EFBFBD>ƽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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GPIO_SetBits(GPIOA, GPIO_Pin_6);
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delay_us(10);
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GPIO_ResetBits(GPIOA, GPIO_Pin_6);
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// delay_ms(SONAR_MAX_WAIT_TIME);
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while (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_7) == RESET )
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{ }
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//<EFBFBD><EFBFBD>SONAR_MAX_WAIT_TIMEʱ<EFBFBD><EFBFBD><EFBFBD>ڵȴ<EFBFBD><EFBFBD>Ƿ<EFBFBD><EFBFBD>л<EFBFBD><EFBFBD><EFBFBD>
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if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_7))
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{ //<EFBFBD><EFBFBD><EFBFBD>ܵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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TIM3->CNT = 0;
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TIM_Cmd(TIM3, ENABLE); //<EFBFBD><EFBFBD>ʼ<EFBFBD><EFBFBD>ʱ
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while (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_7) == SET)
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{ } //<EFBFBD><EFBFBD>ѯ
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TIM_Cmd(TIM3, DISABLE); //<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱ
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p[i] = TIM_GetCounter(TIM3)*1e-6; //<EFBFBD><EFBFBD><EFBFBD><EFBFBD>λ<EFBFBD><EFBFBD>usת<EFBFBD><EFBFBD>Ϊs
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}
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time_s+=p[i];
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delay_ms(10);
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}
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time_s=time_s/5;
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return ( 100*time_s * SoundSpeed / 2); //<EFBFBD><EFBFBD><EFBFBD>ؾ<EFBFBD><EFBFBD><EFBFBD> <EFBFBD><EFBFBD>λcm
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}
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