原创 DS18B20

/********************************
  DS18B20测温程序
  文件名:main.c
  编译：CV1.25.4 由芯艺网站改写

软件缺点是单总线上只能挂一个DS18B20
*******************************/
#include< mega16.h>
#include

#define uint8_t  unsigned char
#define uint16_t unsigned int
#define uint32_t unsigned long int
#define UDRE 5

#define Clr_1Wire DDRB.2=1 //设置为输出，此时由于PORTB.2是低所以输出低
#define Set_1Wire DDRB.2=0//设置为输入，此时由于PORTB.2是低所以程高阻，

                                               //又因为外部有上拉电阻所以相当于设置总线为高
#define Get_1Wire PINB.2

#define DS18B20_READ_ROM 0x33
#define DS18B20_MATCH_ROM 0X55
#define DS18B20_SKIP_ROM 0XCC
#define DS18B20_SEARCH_ROM 0XF0
#define DS18B20_ALARM_SEARCH_ROM 0XEC
#define DS18B20_WRITE_RAM 0X40
#define DS18B20_READ_RAM 0XBE
#define DS18B20_COPY_RAM 0X48
#define DS18B20_CONVERT_TEM 0X44
#define DS18B20_EECALL_EEPROM 0XB8
#define DS18B20_READ_POWER_SUPPLY 0XB4

uint8_t rom_codes[8];

/*******************

总线端口初始化

**********************/
void BusInit(void)
{
       PORTB.2=0;//此口总保持低
       DDRB.2=0; //初始化为输入,用外部上拉电阻保持总线的高电平
}

/*******************************

初始化串口，9600bps，8N1

**********************************/
void init_uart(void)
{
        UCSRA="0x00";
        UCSRB="0x08";
        UCSRC="0x86";
        UBRRH="0x00";
        UBRRL="0x47";
}

void put_c(uint8_t c) //发送采用查询方式
{
        while( !(UCSRA & (1< 

        UDR="c";
}

/*void put_s(unsigned char *ptr)
{
     while (*ptr)
    {
                  put_c(*ptr++);
    }
     put_c(0x0D);
     put_c(0x0A);  //结尾发送回车换行
}*/
//单总线复位
uint8_t ds18b20_reset(void)
{
            uint8_t ret="0";
            Clr_1Wire;
            delay_us(500);  //拉低总线至少480us
            Set_1Wire;
            delay_us(100);//释放总线后等待15-60us
            if((Get_1Wire)==0)//检测到DS18B20把总线拉低
            ret="1";        //复位成功
            delay_us(1000);//等待器件释放总线
            return ret;
}

//单总线读一字节,低位在前
uint8_t ds18b20_read(void)
{
           uint8_t data="0";
           uint8_t  i="0";
          for(i=0;i<8;i++) 
          {
               data>>=1;
              Clr_1Wire; 
              delay_us(2);//此时>1us
             Set_1Wire;
             delay_us(4);//此时<15us
             if(Get_1Wire)
            data|=0x80; 
            delay_us(60);//此时>60us
         }
          return(data);
}

//单总线写一字节，先写低位
void ds18b20_write(uint8_t data)
{
            uint8_t  i="0";
            for(i=0;i<8;i++) 
            {
                      if(data&0x01)
                  {
                          Clr_1Wire;
                         delay_us(8);//8us
                         Set_1Wire; 
                         delay_us(55);//55us
                  }
                   else
                  {
                        Clr_1Wire; 
                        delay_us(55);//55us
                        Set_1Wire;
                       delay_us(20);//8us 
                    } 
                  data>>=1;
          }
}

uint8_t ds18b20_search(uint8_t cmd,uint8_t *point)
{ 
    uint8_t i="0";
   
    if(ds18b20_reset()==0)
    return 0;
    ds18b20_write(cmd);
    for(i=0;i<8;i++)
    {
     point=ds18b20_read();
    }
    return 1; 
}