sht10.c

51单片机实现的温湿度采集监控

#include"SHT10.h"
#include <reg52.h>
#include<intrins.h>
#include<delay.h>


sbit SCK  = P2^0;      //define clock interface 
sbit DATA = P2^1;      //define data interface




typedef union   
{ unsigned int i;      
  float f;  
} value;

/********************************************************************
函数名称:transStartSHT10	启动传输
入口参数：无
返回参数：无
*********************************************************************/
void TransStartSHT10(void)
{    
   DATA=1; SCK=0;                  
   _nop_();  
   SCK=1;  
   _nop_();  
   DATA=0;  
   _nop_();  
   SCK=0;    
   _nop_();_nop_();_nop_();  
   SCK=1;  
   _nop_();  
   DATA=1;         
   _nop_();  
   SCK=0;         
}  

/*********************************************************************
函数名称:connectionResetSHT10	重新连接
入口参数：无
返回参数：无
*********************************************************************/
void ConnectionResetSHT10(void)
{    
  uchar i;   
  DATA=1; SCK=0;                    //Initial state  
  for(i=0;i<9;i++)                  //9 SCK cycles  
  {  
    SCK=1; 
    SCK=0;  
  }  
  TransStartSHT10();                   //transmission start  
}  

/********************************************************************
函数名称：writeSHT10	写数据
入口参数：value
返回参数：error (0成功/1失败)
********************************************************************/

char WriteSHT10(uchar value)
{   
  uchar i,error=0;    
  for (i=0x80;i>0;i/=2)             //shift bit for masking  
  {   
    if (i & value) 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;  
  }  
  DATA=1;                           //release DATA-line  
  SCK=1;                            //clk #9 for ack   
  error=DATA;                       //check ack (DATA will be pulled down by DHT90),DATA在第9个上升沿将被DHT90自动下拉为低电平。  
  _nop_();_nop_();_nop_(); 
  SCK=0; 
  DATA=1;                           //release DATA-line  
  return error;                     //error=1 in case of no acknowledge //返回：0成功，1失败 
}  

/********************************************************************
函数名称:readSHT10	读数据
入口参数：ack
返回参数：val（ack=0时读数据，返回val）
*********************************************************************/

char ReadSHT10(uchar ack)
{   
  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  
    if (DATA) val=(val | i);        //read bit    
        _nop_();_nop_();_nop_();        //pulswith approx. 5 us 
    SCK=0;               
  }  
  if(ack==1)DATA=0;                 //in case of "ack==1" pull down DATA-Line  
  else DATA=1;                      //如果是校验(ack==0)，读取完后结束通讯 
  _nop_();_nop_();_nop_();          //pulswith approx. 5 us  
  SCK=1;                            //clk #9 for ack  
  _nop_();_nop_();_nop_();          //pulswith approx. 5 us   
  SCK=0;                  
  _nop_();_nop_();_nop_();          //pulswith approx. 5 us  
  DATA=1;                           //release DATA-line  
  return val;  
}  

/*********************************************************************
函数名称:measureSHT10 测量温度 
入口参数:*p_value,*p_checksum,mode
返回参数:error(0成功/1失败)
*********************************************************************/

char MeasureSHT10(uchar *p_value, uchar *p_checksum, uchar mode)
{   
  unsigned error=0;  
  uchar i;  
  
  TransStartSHT10();                   //transmission start  
  switch(mode){                     //send command to sensor  
    case 01  : error+=WriteSHT10(MEASURE_TEMP); break;  
    case 02  : error+=WriteSHT10(MEASURE_HUMI); break;  
    default     : break;     
  }  
  for (i=0;i<110;i++) {delay(2);if(DATA==0) break;} //wait until sensor has finished the measurement  
  if(DATA) error+=1;                // or timeout (~2 sec.) is reached  
  *(p_value)  =ReadSHT10(ACK);    //read the first byte (MSB)  
  *(p_value+1)=ReadSHT10(ACK);    //read the second byte (LSB)  
  *p_checksum =ReadSHT10(noACK);  //read checksum  
  return error;  
}  

/********************************************************************
函数名称: calcSHT10						计算温度和相对湿度值
入口参数：*p_humidity ,*p_temperature
返回参数：无
********************************************************************/
void CalcSHT10(float *p_humidity ,float *p_temperature)
// calculates temperature [C] and humidity [%RH]  
// input :  humi [Ticks] (12 bit)  
//          temp [Ticks] (14 bit) 
// output:  humi [%RH] 
//          temp [C] 
{ 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 T1=0.01;             // for 14 Bit @ 5V 
  const float T2=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 [C] 

  t_C=t*0.01 - 40;                  //calc. temperature from ticks to [C] 
  rh_lin=C3*rh*rh + C2*rh + C1;     //calc. humidity from ticks to [%RH] 
  rh_true=(t_C-25)*(T1+T2*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 

  *p_temperature=t_C;               //return temperature [C] 
  *p_humidity=rh_true;              //return humidity[%RH] 
}

/********************************************************************
函数名称: getSHT10()
入口参数：float temp,float humi
返回参数：无
********************************************************************/
void GetSHT10(float *temp,float *humi)
{
	 value humi_val,temp_val; 
     uchar error,checksum; 
	 error=0;  
          error+=MeasureSHT10((uchar*) &humi_val.i,&checksum,HUMI);  //measure humidity  
          error+=MeasureSHT10((uchar*) &temp_val.i,&checksum,TEMP);  //measure temperature  
          if(error!=0) ConnectionResetSHT10();                 //in case of an error: connection reset  
          else  
          { humi_val.f=(float)humi_val.i;                   //converts integer to float 
            temp_val.f=(float)temp_val.i;                   //converts integer to float 
            CalcSHT10(&humi_val.f,&temp_val.f);            //calculate humidity, temperature 
			
			*temp=temp_val.f;
			*humi=humi_val.f;

		  }
}