sht.c

DS18B20用来测温度十分方便

//***********************************************************************
//FILE: sht.c
//功能:	温湿渡传感器SHT11的全部操作
//***********************************************************************

//***********************************************************************
#include "main.h"
#include "intrins.h"
#include "tools.h"
#include "sht.h"
#include "stdio.h"
#include "math.h"
//***********************************************************************
#define  _Nop()  _nop_(),_nop_(),_nop_()     //定义空指令

/*************************************
名称:  s_write_byte
功能:  写入一个字节函数
*************************************/
char s_write_byte(uchar tvalue)
// writes a byte on the Sensibus and checks the acknowledge 
{ 
  uchar i,error=0; 
  for (i=0x80;i>0;i/=2)             //shift bit for masking
  { 
  	if (i & tvalue) 
    DATA=1;                         //masking value with i , write to SENSI-BUS
    else DATA=0;                        
    SCK=1;                          //clk for SENSI-BUS
    _Nop();_Nop();_Nop();           //pulswith approx. 5 us  	
    SCK=0;
    _Nop();
  }
  DATA=1;                           //release DATA-line
  SCK=1;                            //clk #9 for ack 
  error=DATA;                       //check ack (DATA will be pulled down by SHT11)
  SCK=0;
  return error;                     //error=1 in case of no acknowledge

}


/*************************************
名称:  s_read_byte
功能:  读出一个字节函数
*************************************/
char s_read_byte(uchar ack)
// reads a byte form the Sensibus and gives an acknowledge in case of "ack=1" 
{ 
  uchar i,val=0;
  DATA=1;                           //release DATA-line
  for (i=0x80;i>0;i/=2)             //shift bit for masking
  {
  	SCK=1;                          //clk for SENSI-BUS
  	_Nop();                         
    if (DATA) val=(val | i);        //read bit  
    SCK=0;                         
    _Nop(); 					 
  }
  DATA=!ack;                        //in case of "ack==1" pull down DATA-Line
  SCK=1;                            //clk #9 for ack
  _Nop();                           //pulswith approx. 5 us 
  SCK=0;
  _Nop();						            
  DATA=1;                           //release DATA-line
  return val;
}


/*************************************
名称:  s_transstart
功能:  传输开始
*************************************/
void s_transstart(void)
// generates a transmission start 
//       _____         ________
// DATA:      |_______|
//           ___     ___
// SCK : ___|   |___|   |______
{  

   DATA=1; SCK=0;                   //Initial state
   _Nop();
   SCK=1;
   _Nop();
   DATA=0;
   _Nop();
   SCK=0;  
   _Nop();
   SCK=1;
   _Nop();
   DATA=1;		   
   _Nop();
   SCK=0;		   
}

/*************************************
名称:  s_connectionreset
功能:  重新连接
*************************************/
void s_connectionreset(void)
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
//       _____________________________________________________         ________
// DATA:                                                      |_______|
//          _    _    _    _    _    _    _    _    _        ___     ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______|   |___|   |______
{  
  uchar i; 
  DATA=1; SCK=0;                    //Initial state
  for(i=0;i<9;i++)                  //9 SCK cycles
  { 
  	 SCK=1;
  	_Nop();               
     SCK=0;
    _Nop();
  }
  s_transstart();                   //transmission start
}



/*************************************
名称:  s_read_statusreg
功能:  读状态寄存器
*************************************/
/*
char s_read_statusreg(unsigned char *p_value, unsigned char *p_checksum)
// reads the status register with checksum (8-bit)
{ 
  uchar error=0;
  s_transstart();                   //transmission start
  error=s_write_byte(STATUS_REG_R); //send command to sensor
  *p_value=s_read_byte(ACK);        //read status register (8-bit)
  *p_checksum=s_read_byte(noACK);   //read checksum (8-bit) 
    Prints("status=");
    Puthexbyte(*p_value);
    Prints("\r\n"); 
  return error;                     //error=1 in case of no response form the sensor
}
*/

/*************************************
名称:  s_write_statusreg
功能:  写状态寄存器
*************************************/
/*
char s_write_statusreg(unsigned char *p_value)
// writes the status register with checksum (8-bit)
{ 
  uchar error=0;
  //s_transstart();                   //transmission start
   s_connectionreset();             //后加
  error+=s_write_byte(STATUS_REG_W);//send command to sensor
  error+=s_write_byte(*p_value);    //send value of status register
  return error;                     //error>=1 in case of no response form the sensor
}
*/

/*************************************
名称:  s_softreset
功能:  重置寄存器
*************************************/
/*
char s_softreset(void)
// resets the sensor by a softreset 
{ 

  uchar error=0;  
  s_connectionreset();              //reset communication
  error+=s_write_byte(RESET);       //send RESET-command to sensor
  return error;                     //error=1 in case of no response form the sensor
}
*/

/*************************************
名称:  s_humi
功能:  测量湿度
*************************************/
char s_humi(uchar *p_value, uchar *p_checksum)
// measure the huminity
{ 
	
  uchar error=0;
  uint i;
  s_transstart();                   //transmission start
  error=s_write_byte(MEASURE_HUMI); //send messure huminity command to sensor
  for (i=0;i<65535;i++) if(DATA==0) break; //wait until sensor has finished the measurement
  if(DATA) error+=1;                // or timeout (~2 sec.) is reached
  *(p_value)  =s_read_byte(ACK);    //read the first byte  (MSB)
  *(p_value+1)=s_read_byte(ACK);    //read the second byte (LSB)
  *p_checksum=s_read_byte(noACK);   //read checksum (8-bit) 
    Prints("\r\n");
    Prints("humi=");
    Puthexbyte(*p_value);
    Puthexbyte(*(p_value+1));
    Prints("\r\n");
    return error;                     //error=1 in case of no response form the sensor
}

/*************************************
名称:  s_temp
功能:  测量温度
*************************************/
char s_temp(uchar *p_value, uchar *p_checksum)
// measure the temprature
{ 
  uchar error=0;
  uint i;
  s_transstart();                   //transmission start
  error=s_write_byte(MEASURE_TEMP); //send messure tempture command to sensor
  for (i=0;i<65535;i++) if(DATA==0) break; //wait until sensor has finished the measurement
  if(DATA) error+=1;                // or timeout (~2 sec.) is reached
  *(p_value)  =s_read_byte(ACK);    //read the first byte  (MSB)
  *(p_value+1)=s_read_byte(ACK);    //read the second byte (LSB)
  *p_checksum=s_read_byte(noACK);   //read checksum (8-bit) 
    Prints("temp=");
    Puthexbyte(*p_value);
    Puthexbyte(*(p_value+1));
    Prints("\r\n");
    return error;                   //error=1 in case of no response form the sensor
}

/*************************************
名称:  calc_sth11
功能:  计算温湿渡的值
*************************************/
void calc_sth11(float *p_humidity ,float *p_temperature)

// calculates temperature  and humidity [%RH] 
// input :  humi [Ticks] (12 bit) 
//          temp [Ticks] (14 bit)
// output:  humi [%RH]
//          temp 
{ 
  const float C1=-4.0;               // for 12 Bit
  const float C2=+0.0405;            // for 12 Bit
  const float C3=-0.0000028;         // for 12 Bit
  const float T11=+0.01;             // for 14 Bit @ 5V
  const float T22=+0.00008;          // for 14 Bit @ 5V	

  float rh=*p_humidity;              // rh:      Humidity [Ticks] 12 Bit 
  float t=*p_temperature;            // t:       Temperature [Ticks] 14 Bit
  float rh_lin;                      // rh_lin:  Humidity linear
  float rh_true;                     // rh_true: Temperature compensated humidity
  float t_C;                         // t_C   :  Temperature 

  t_C=t*0.01 - 40;                   //calc. temperature from ticks to
  rh_lin=C3*rh*rh + C2*rh + C1;      //calc. humidity from ticks to [%RH]
  rh_true=(t_C-25)*(T11+T22*rh)+rh_lin;   //calc. temperature compensated humidity [%RH]
  if(rh_true>100)rh_true=100;        //cut if the value is outside of
  if(rh_true<0.1)rh_true=0.1;        //the physical possible range
  Humi=rh_true*10;
  Temp=t_C*10;
}



/*************************************
名称:  calc_sth11
功能:  计算露点值
*************************************/
/*
float calc_dewpoint(float h,float t)
// calculates dew point
// input:   humidity [%RH], temperature
// output:  dew point 
{ float logEx,dew_point;
  logEx=0.66077+7.5*t/(237.3+t)+(log10(h)-2);
  dew_point = (logEx - 0.66077)*237.3/(0.66077+7.5-logEx);
  return dew_point;
}
*/