49 lines
1.0 KiB
C
49 lines
1.0 KiB
C
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#include <ultrasound.h>
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#include "intrins.h"
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sbit Tx = P1^0;
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sbit Rx = P1^1;
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void Delay12us() //@12.000MHz
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{
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unsigned char i;
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_nop_();
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_nop_();
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i = 38;
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while (--i);
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}
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void Ut_Wave_Init() //<2F><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>8<EFBFBD><38>40Mhz<68>ķ<EFBFBD><C4B7><EFBFBD><EFBFBD>ź<EFBFBD>
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{
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unsigned char i;
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for(i=0; i<8; i++)
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{
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Tx = 1;
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Delay12us();
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Tx = 0;
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Delay12us();
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}
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}
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unsigned char Ut_Wave_Data() //超声波距离读取函数
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{
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unsigned int time;//时间储存变量
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CMOD = 0x00;//配置PCA工作模式
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CH = CL = 0;//复位计数值 等待超声波信号发出
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Ut_Wave_Init();//发送超声波信号
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CR = 1;//开始计时
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while((Rx == 1) && (CF == 0));//等待接受返回信号或者定时器溢出
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CR = 0;//停止计时
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if(CF == 0) //定时器没有溢出
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{
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time = CH << 8 | CL;//读取当前时间
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return (time * 0.017);//返回距离值
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}
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else
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{
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CF = 0;//清除溢出标志位
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return 0;
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}
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}
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