56 lines
1.0 KiB
C
56 lines
1.0 KiB
C
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#include "Ultrasonic.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(void) //@12.000MHz
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{
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unsigned char data i;
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_nop_();
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_nop_();
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i = 33; // 38
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while (--i)
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;
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}
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void Ut_Wave_Init()
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{
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unsigned char i;
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// <20><><EFBFBD><EFBFBD>8<EFBFBD><38>40kHz<48>ķ<EFBFBD><C4B7><EFBFBD>
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// f=40kHz->T=1/f=0.000025s=25us
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// 12.5us 1 12.5us 0
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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()
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{
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unsigned int time;
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CH = CL = 0; // <20><><EFBFBD><EFBFBD>PCA<43>Ĵ<EFBFBD><C4B4><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ
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CCON = 0; // <20><>ʼ<EFBFBD><CABC>PCA<43><41><EFBFBD>ƼĴ<C6BC><C4B4><EFBFBD>/PCA<43><41>ʱ<EFBFBD><CAB1>ֹͣ/<2F><><EFBFBD><EFBFBD>CF/
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EA = 0; // <20>ر<EFBFBD><D8B1><EFBFBD><EFBFBD>ж<EFBFBD>
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Ut_Wave_Init(); // <20><><EFBFBD>ͳ<EFBFBD><CDB3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ź<EFBFBD>
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EA = 1; // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ж<EFBFBD>
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CR = 1; // PCA<43><41>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD>
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while (Rx && !CF) // TF1
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; // <20>ȴ<EFBFBD><C8B4><EFBFBD><EFBFBD><EFBFBD>
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CR = 0; // PCAֹͣ<CDA3><D6B9><EFBFBD><EFBFBD>
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if (CF == 0)
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{
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time = CH << 8 | CL; // <20><>λΪ<CEBB><CEAA><EFBFBD><EFBFBD>
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// L=V*T/2
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return (time * 0.017); // <20><><EFBFBD>صĵ<D8B5>λ<EFBFBD><CEBB>cm
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}
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else
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{
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CF = 0;
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return 0;
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}
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}
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