Andy0613
109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
#include "ds18b20.h"
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/*
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* ????????DS18B20_Reset
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* ???? ????¦ËDS18B20????????????
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* ???? ????
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* ??? ??1=?????0=??????
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*/
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bit DS18B20_Reset(void)
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{
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unsigned int i;
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unsigned char presence;
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DS18B20_DQ = 0; /* ????????480~960us */
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for(i=250; i>0; i--); /* DJNZ???: 250*2=500us */
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DS18B20_DQ = 1; /* ????????DS18B20????15~60us??????60~240us */
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for(i=10; i>0; i--); /* DJNZ: 10*2=20us, ?????????? */
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presence = DS18B20_DQ; /* ???????????(0=?????1=??????) */
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for(i=200; i>0; i--); /* DJNZ: 200*2=400us, ????????? */
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return (presence == 0); /* ????1?????????????? */
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}
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/*
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* ????????DS18B20_WriteByte
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* ???? ????DS18B20§Õ????????(LSB????)
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* ???? ??dat=?§Õ???????
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* ??? ????
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*/
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void DS18B20_WriteByte(uchar dat)
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{
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unsigned char i, j;
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for(i=0; i<8; i++)
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{
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DS18B20_DQ = 0; /* ??????????§Õ?? */
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if(dat & 0x01) /* §Õ1????????? */
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DS18B20_DQ = 1;
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else /* §Õ0?????????? */
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DS18B20_DQ = 0;
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for(j=35; j>0; j--); /* DJNZ: 35*2=70us, ?????>=60us */
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DS18B20_DQ = 1; /* ??????? */
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dat >>= 1; /* ???¦Ë(LSB first) */
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}
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}
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/*
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* ????????DS18B20_ReadByte
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* ???? ????DS18B20?????????(LSB????)
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* ???? ????
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* ??? ????????????
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*/
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uchar DS18B20_ReadByte(void)
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{
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unsigned char i, j, dat = 0;
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for(i=0; i<8; i++)
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{
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DS18B20_DQ = 0; /* ?????????????? */
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DS18B20_DQ = 1; /* ??????? */
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for(j=7; j>0; j--); /* DJNZ: 7*2=14us, ???DS18B20???????(~15us) */
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dat >>= 1; /* ?????¦Ë */
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if(DS18B20_DQ)
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dat |= 0x80; /* LSB first?????????????¦Ë??????¦Ë */
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for(j=23; j>0; j--); /* DJNZ: 23*2=46us, ?????>=60us */
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}
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return dat;
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}
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/*
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* ????????DS18B20_StartConvert
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* ???? ??????DS18B20??????
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* ???? ????
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* ??? ????
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*/
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void DS18B20_StartConvert(void)
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{
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if(!DS18B20_Reset()) return; /* ??¦Ë???????? */
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DS18B20_WriteByte(0xCC); /* ????ROM */
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DS18B20_WriteByte(0x44); /* ????????? */
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}
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/*
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* ????????DS18B20_ReadTemp
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* ???? ?????DS18B20??????(16¦Ë)
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* ???? ??temp=??????????????
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* ??? ??1=????????0=DS18B20¦Ä???
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*/
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bit DS18B20_ReadTemp(int *temp)
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{
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uchar tempL, tempH;
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int raw;
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if(!DS18B20_Reset()) return 0; /* ??¦Ë???????? */
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DS18B20_WriteByte(0xCC); /* ????ROM */
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DS18B20_WriteByte(0xBE); /* ??????? */
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tempL = DS18B20_ReadByte(); /* ?????????? */
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tempH = DS18B20_ReadByte(); /* ?????????? */
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raw = (tempH << 8) | tempL; /* ???16¦Ë???? */
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*temp = raw;
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return 1;
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} |