#include "ds18b20.h"

/*
 * ????????DS18B20_Reset
 * ????  ????¦ËDS18B20????????????
 * ????  ????
 * ???  ??1=?????0=??????
 */
bit DS18B20_Reset(void)
{
    unsigned int i;
    unsigned char presence;
    
    DS18B20_DQ = 0;          /* ????????480~960us */
    for(i=250; i>0; i--);   /* DJNZ???: 250*2=500us */
    DS18B20_DQ = 1;          /* ????????DS18B20????15~60us??????60~240us */
    for(i=10; i>0; i--);    /* DJNZ: 10*2=20us, ?????????? */
    
    presence = DS18B20_DQ;   /* ???????????(0=?????1=??????) */
    
    for(i=200; i>0; i--);   /* DJNZ: 200*2=400us, ????????? */
    
    return (presence == 0);  /* ????1?????????????? */
}

/*
 * ????????DS18B20_WriteByte
 * ????  ????DS18B20§Õ????????(LSB????)
 * ????  ??dat=?§Õ???????
 * ???  ????
 */
void DS18B20_WriteByte(uchar dat)
{
    unsigned char i, j;

    for(i=0; i<8; i++)
    {
        DS18B20_DQ = 0;     /* ??????????§Õ?? */
        if(dat & 0x01)      /* §Õ1????????? */
            DS18B20_DQ = 1;
        else                /* §Õ0?????????? */
            DS18B20_DQ = 0;
        for(j=35; j>0; j--); /* DJNZ: 35*2=70us, ?????>=60us */
        DS18B20_DQ = 1;     /* ??????? */
        dat >>= 1;          /* ???¦Ë(LSB first) */
    }
}

/*
 * ????????DS18B20_ReadByte
 * ????  ????DS18B20?????????(LSB????)
 * ????  ????
 * ???  ????????????
 */
uchar DS18B20_ReadByte(void)
{
    unsigned char i, j, dat = 0;

    for(i=0; i<8; i++)
    {
        DS18B20_DQ = 0;     /* ?????????????? */
        DS18B20_DQ = 1;     /* ??????? */
        for(j=7; j>0; j--); /* DJNZ: 7*2=14us, ???DS18B20???????(~15us) */

        dat >>= 1;          /* ?????¦Ë */
        if(DS18B20_DQ)
            dat |= 0x80;    /* LSB first?????????????¦Ë??????¦Ë */

        for(j=23; j>0; j--); /* DJNZ: 23*2=46us, ?????>=60us */
    }
    return dat;
}

/*
 * ????????DS18B20_StartConvert
 * ????  ??????DS18B20??????
 * ????  ????
 * ???  ????
 */
void DS18B20_StartConvert(void)
{
    if(!DS18B20_Reset()) return;    /* ??¦Ë???????? */
    DS18B20_WriteByte(0xCC);        /* ????ROM */
    DS18B20_WriteByte(0x44);        /* ????????? */
}

/*
 * ????????DS18B20_ReadTemp
 * ????  ?????DS18B20??????(16¦Ë)
 * ????  ??temp=??????????????
 * ???  ??1=????????0=DS18B20¦Ä???
 */
bit DS18B20_ReadTemp(int *temp)
{
    uchar tempL, tempH;
    int raw;
    
    if(!DS18B20_Reset()) return 0;  /* ??¦Ë???????? */
    DS18B20_WriteByte(0xCC);        /* ????ROM */
    DS18B20_WriteByte(0xBE);        /* ??????? */
    
    tempL = DS18B20_ReadByte();     /* ?????????? */
    tempH = DS18B20_ReadByte();     /* ?????????? */
    
    raw = (tempH << 8) | tempL;     /* ???16¦Ë???? */
    *temp = raw;
    
    return 1;
}