DS1820 khó quá....

[picpen]

/*-------1-wire definitions-------*/ 
#define ONE_WIRE_PIN PIN_E2

/*******************1-wire communication functions********************/ 

/************onewire_reset*************************************************/ 
/*This function initiates the 1wire bus */ 
/* */ 
/*PARAMETERS: */ 
/*RETURNS: */ 
/*********************************************************************/ 

void onewire_reset()  // OK if just using a single permanently connected device 
{ 
 output_low(ONE_WIRE_PIN); 
 delay_us( 500 ); // pull 1-wire low for reset pulse 
 output_float(ONE_WIRE_PIN); // float 1-wire high 
 delay_us( 500 ); // wait-out remaining initialisation window. 
 output_float(ONE_WIRE_PIN); 
} 

/*********************** onewire_write() ********************************/ 
/*This function writes a byte to the sensor.*/ 
/* */ 
/*Parameters: byte - the byte to be written to the 1-wire */ 
/*Returns: */ 
/*********************************************************************/ 

void onewire_write(int data) 
{ 
 int count; 

 for (count=0; count<8; ++count) 
 { 
  output_low(ONE_WIRE_PIN); 
  delay_us( 2 ); // pull 1-wire low to initiate write time-slot. 
  output_bit(ONE_WIRE_PIN, shift_right(&data,1,0)); // set output bit on 1-wire 
  delay_us( 60 ); // wait until end of write slot. 
  output_float(ONE_WIRE_PIN); // set 1-wire high again, 
  delay_us( 2 ); // for more than 1us minimum. 
 } 
} 

/*********************** read1wire() *********************************/ 
/*This function reads the 8 -bit data via the 1-wire sensor. */ 
/* */ 
/*Parameters: */ 
/*Returns: 8-bit (1-byte) data from sensor */ 
/*********************************************************************/ 

int onewire_read() 
{ 
 int count, data; 

 for (count=0; count<8; ++count) 
 { 
  output_low(ONE_WIRE_PIN); 
  delay_us( 2 ); // pull 1-wire low to initiate read time-slot. 
  output_float(ONE_WIRE_PIN); // now let 1-wire float high, 
  delay_us( 8 ); // let device state stabilise, 
  shift_right(&data,1,input(ONE_WIRE_PIN)); // and load result. 
  delay_us( 120 ); // wait until end of read slot. 
 } 

 return( data ); 
} 


float ds1820_read()
{ 
 int8 busy=0, temp1, temp2; 
 signed int16 temp3; 
 float result; 

 onewire_reset(); 
 onewire_write(0xCC); 
 onewire_write(0x44); 

 while (busy == 0) 
  busy = onewire_read(); 

 onewire_reset(); 
 onewire_write(0xCC); 
 onewire_write(0xBE); 
 temp1 = onewire_read(); 
 temp2 = onewire_read(); 
 temp3 = make16(temp2, temp1); 
  
// result = (float) temp3 / 2.0;   //Calculation for DS18S20 with 0.5 deg C resolution 
 result = (float) temp3 / 16.0;  //Calculation for DS18B20 with 0.1 deg C resolution 
  
 delay_ms(200); 
 return(result); 
}

Chương trình này bạn nạp vào mạch của bạn là chạy ok ngay.

Bạn muốn giao tiếp với bất kỳ chân nào của chíp, chỉ cần cấu hình lại chân giao tiếp bằng dòng lệnh này: #define ONE_WIRE_PIN PIN_E2