ds18b20.c

DS18B20的AVR驱动程序

	  t=1;
	else
	  t=0;
	delayUs(8);	 	//14.92us
	delayUs(8);
	delayUs(8);	 	//14.92us
	RLS_DS18B20;		//释放总线
	delayUs(12);
	return(t);
		
		
}

/**********************************************************************
functionName: BYTE readByteDS18B20(void)
description ：读DS18B20一个字节
**********************************************************************/
unsigned char OWReadbyte(void)
{
	unsigned char i;
	unsigned char retVal=0;


	RLS_DS18B20;		//释放总线
	for(i=8;i>0;i--)
	{
	 	retVal>>=1;
	
	  	if (OWReadBit())
		  retVal|=0x80; 	
	}

	delayUs(1);	 		//2.71us(大于1us就行了)
	return(retVal);
}

/////////////////////////////////////////
void OWWriteBit(unsigned char temp)
{
    HLD_DS18B20;		//Maga16控制总线
	CLR_DS18B20;		//强制拉低
	if(temp)
	  //RLS_DS18B20;		//释放总线
      SET_DS18B20;
	else
	  CLR_DS18B20;		//强制拉低
	delayUs(35);	 	//60us
			 	
	RLS_DS18B20;		//释放总线
	delayUs(50);
}

/**********************************************************************
functionName: BYTE readByteDS18B20(void)
description ：写DS18B20一个字节
**********************************************************************/
void OWWriteByte(unsigned char wb)
{
	unsigned char i;
	unsigned char temp;
	RLS_DS18B20;		//释放总线
	for(i=0;i<8;i++)
	{
		temp=wb>>i;
		temp&=0x01;
		OWWriteBit(temp);	 	
	}
}

///////////////////////////////////////////////
void delayms(void)
{
   unsigned int i;
   int j;
   for(j=0;j<10;j++)
   {
      for(i=0;i<40000;i++);
   }
}


unsigned char OWSearch(void)
{
    unsigned char id_bit_number;
    unsigned char last_zero, rom_byte_number, search_result;
    unsigned char  id_bit, cmp_id_bit;
    unsigned char rom_byte_mask, search_direction;
    // initialize for search
    id_bit_number = 1;
    last_zero = 0;
    rom_byte_number = 0;
    rom_byte_mask = 1;
    search_result = 0;
    crc8 = 0;
    // if the last call was not the last one
    if (!LastDeviceFlag)
    {
       // 1-Wire reset
       if (!OWReset())
       {
          // reset the search
          LastDiscrepancy = 0;
          LastDeviceFlag = 0;
          LastFamilyDiscrepancy = 0;
          return 0;
       }
       // issue the search command
       OWWriteByte(0xf0);
       // loop to do the search
       do
       {
          // read a bit and its complement
          id_bit = OWReadBit();
          cmp_id_bit = OWReadBit();
          // check for no devices on 1-Wire
          if ((id_bit == 1) && (cmp_id_bit == 1))
             break;
          else
          {
             // all devices coupled have 0 or 1
             if (id_bit != cmp_id_bit)
                search_direction = id_bit; // bit write value for search
             else
             {
                // if this discrepancy if before the Last Discrepancy
                // on a previous next then pick the same as last time
                if (id_bit_number < LastDiscrepancy)
                   search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
                else
                   // if equal to last pick 1, if not then pick 0
                   search_direction = (id_bit_number == LastDiscrepancy);
                // if 0 was picked then record its position in LastZero
                if (search_direction == 0)
                {
                   last_zero = id_bit_number;
                   // check for Last discrepancy in family
                   if (last_zero < 9)
                      LastFamilyDiscrepancy = last_zero;
                }
             }
             // set or clear the bit in the ROM byte rom_byte_number
             // with mask rom_byte_mask
             if (search_direction == 1)
                ROM_NO[rom_byte_number] |= rom_byte_mask;
             else
                ROM_NO[rom_byte_number] &= ~rom_byte_mask;
             // serial number search direction write bit
             OWWriteBit(search_direction);
             // increment the byte counter id_bit_number
             // and shift the mask rom_byte_mask
             id_bit_number++;
             rom_byte_mask <<= 1;
             // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
             if (rom_byte_mask == 0)
             {
                docrc8(ROM_NO[rom_byte_number]); // accumulate the CRC
                rom_byte_number++;
                rom_byte_mask = 1;
             }
          }
       }while(rom_byte_number < 8); // loop until through all ROM bytes 0-7
       // if the search was successful then
       if (!((id_bit_number < 65) || (crc8 != 0)))
       {
          // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
          LastDiscrepancy = last_zero;
          // check for last device
          if (LastDiscrepancy == 0)
             LastDeviceFlag = 1;
          // check for last family group
          if (LastFamilyDiscrepancy == LastDiscrepancy)
             LastFamilyDiscrepancy = 0;
          search_result = 1;
       }
    }
    // if no device found then reset counters so next 'search' will be like a first
    if (!search_result || !ROM_NO[0])
    {
       LastDiscrepancy = 0;
       LastDeviceFlag = 0;
       LastFamilyDiscrepancy = 0;
       search_result = 0;
    }
    return search_result;
}

unsigned char docrc8(unsigned char value)
{
// See Application Note 27
// TEST BUILD
   crc8 = dscrc_table[crc8 ^ value];
   return crc8;
}

int OWFirst(void)
{
// reset the search state
    LastDiscrepancy = 0;
    LastDeviceFlag = 0;
    LastFamilyDiscrepancy = 0;
    return OWSearch();
}

int OWNext(void)
{
// leave the search state alone
    return OWSearch();
}


void init_port(void)
{
    PORTB=0b11111111;  //
    DDRB=0b00101100;  //PB0,PB1,SCK MOSI SS输出  MISO输入
   
    PORTC=0b11111010;
    DDRC=0Xbe;   //reset AD0输入,其余输出

	RecMode;  //上电接收模式
   
    PORTD=0b11111111;
    DDRD=0b00000010; //PD2~PD7输入,RXD输入,TXD输出

}

void init_timer1(void)
{    

    TCCR1A=0;
	TCCR1B= (1<<CS12); //256预分频  晶振为7.3728MHz  一条指令大约34.72us
	TCNT1=65535-((7372800/256)*50)/1000;   //50ms中断初值
	//TIMSK=(1<<TOIE1); //中断允许
	TIMSK1=(1<<TOIE1); //中断允许
	
}

void init_USART(void)//USART 初始化
{   

   UCSR0A = 0x00;
   UCSR0B=(1<<RXCIE0)|(1<<RXEN0)|(1<<TXEN0); //使能接收中断，使能接收，使能发送
   UCSR0C=0x06;  //异步，8位数据，无奇偶校验，一个停止位
   

   UBRR0L= (F_CPU/BAUDRATE/16-1)%256;
   UBRR0H= (F_CPU/BAUDRATE/16-1)/256;

}


SIGNAL(SIG_OVERFLOW1)  //T1中断
{
   TCNT1=65535-((7372800/256)*50)/1000;

   R_Delay++;
   if (R_Delay>=20)
   {
      R_Delay=0;
      R_Status|=BIT0;

   }


}

void put_c(unsigned char c) //发送采用查询方式
{    
    

	while( !(UCSR0A & (1<<UDRE0)) );
	UDR0=c;



}

void put_s(unsigned char *s,unsigned char Len)
{
   unsigned char i;
        

   TraMode;

   NOP;NOP;NOP;

   for(i=0;i<Len;i++)
   {
      put_c(*s++);
	 
   }

   _delay_ms(5);
 
   RecMode;
}


SIGNAL(SIG_USART_RECV) //串口接收中断服务程序
{    

    PC_COMMAND=UDR0;


    RX_BUFFER[RX_index]=PC_COMMAND;		//保存数据到数组里面
	RX_index++;
	if (RX_index>=sizeof(RX_BUFFER)) RX_index=0;		//防止数组溢出

    

}