sht11.h

C语言编写的温湿度传感器SHT11与51单片机的接口驱动程序

#include "math.h"         /*Keil library*/ 
#include "stdio.h"        /*Keil library*/
#include "absacc.h"

#define ACK 1
#define noACK 0
#define measure_temp 0x03 //测量温度命令
#define measure_humi 0x05 //测量湿度命令
#define RESET        0x1e //软启动

#define     uchar    unsigned   char
#define     uint     unsigned   int
#define     ulong    unsigned   long

sbit   DATA = P1^0;
sbit   SCK  = P1^1;

uint sht11[2];

typedef union                      /*保存所测得的温度＆湿度值*/
{ 
  uint  i;
  float f;
}value;

typedef struct __SHT11__
{
	unsigned char gewei;
	unsigned char shiwei;
	unsigned char DateString1[5];
    unsigned char DateString2[5];
}SHT11;

char write_byte(unsigned char value)
// writes a byte on the Sensibus and checks the acknowledge 
{ 
  unsigned char i,error=0;  
  for (i=0x80;i>0;i/=2)             /*连续向右移动8位*/
  { 
    if (i & value) DATA=1;          /*把相应的位送数据线*/
    else DATA=0;                        
    SCK=1;                          /*时序脉冲，应严格按着此标准*/
    _nop_();
    _nop_();
    _nop_();                        /*大约0.5us*/	
    SCK=0;
  }
  DATA=1;                           /*释放数据线*/
  SCK=1;                            /*第9位作为响应位*/
  error=DATA;                       /*检测响应情况，如果有响应数据线就会被SHT10拉低*/
  SCK=0;        
  return error;                     /*返回1表示没响应*/
}

char read_byte(unsigned char ack)
{ 
  unsigned char i,val=0;
  DATA=1;                           /*释放数据线*/
  for (i=0x80;i>0;i/=2)             /*连续向右移动8位*/
  { SCK=1;                          /*clk for SENSI-BUS*/
    if (DATA) val=(val | i);        /*read bit */ 
    SCK=0;  					 
  }
  DATA=!ack;                        /*当ack＝1时拉低数据线*/
  SCK=1;                            /*clk #9 for ack*/
  _nop_();_nop_();_nop_();          /*pulswith approx. 5 us */
  SCK=0;						    
  DATA=1;                           /*释放数据线*/
  return val;
}

void transstart(void)
{
    DATA=1; 
    SCK=0;                   //初始状态
    _nop_();
    SCK=1;
    _nop_();
    DATA=0;
    _nop_();
    SCK=0;
    _nop_();_nop_();_nop_();
    SCK=1;
    _nop_();
    DATA=1;
	_nop_();
    SCK=0;
}

void connectionreset(void)//复位：当DATA线处于高低平时，触发SCK9次以上（含9次），此后应接发一个"传输开始"命令
{  
  unsigned char i; 
  DATA=1; SCK=0;                    /*Initial state*/
  for(i=0;i<9;i++)                  /*9 SCK cycles*/
  { 
    SCK=1;
    SCK=0;
  }
  transstart();                   /*transmission start*/
}

char s_measure(unsigned char *p_value, unsigned char *p_checksum, unsigned char mode)

/*makes a measurement (humidity/temperature) with checksum*/ 
{ 
  unsigned error=0;
  unsigned int i;

  transstart();                   /*transmission start*/
  switch(mode){                     /*send command to sensor*/
    case 0	: error+=write_byte(measure_temp); break;
    case 1	: error+=write_byte(measure_humi); break;
    default     : break;	 
  }
  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)  =read_byte(ACK);           /*read the first byte (MSB)*/
  *(p_value+1)=read_byte(ACK);           /*read the second byte (LSB)*/
  *p_checksum =read_byte(noACK);         /*read checksum*/
  return error;
}

//温湿度值标度变换及温度补偿
void calc_sth11(float *p_humidity ,float *p_temperature)      
{ 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 [癈]*/ 

  t_C=t*0.01 - 40;                     /*calc. temperature from ticks to [癈]*/
  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 [癈]*/
  *p_humidity=rh_true;                 /*return humidity[%RH]*/
}
/*************************************************************************************/
void DateToString(SHT11 *SHT,float datax,float datax1)
{
	uint i;
    i=(int)datax;
	SHT->shiwei=i/10;
	SHT->gewei =i%10;
    SHT->DateString1[0] = SHT->shiwei + '0';
	SHT->DateString1[1] = SHT->gewei + '0';
	i=(int)((datax-i)*10); 
	SHT->DateString1[2] ='.';
	SHT->DateString1[3] = i + '0';
	SHT->DateString1[4] = '\0'; 
    if(0<=i<=4)
      sht11[0] = (int)datax;
    else
      sht11[0] = (int)(datax+1);

    i=(int)datax1;
	SHT->shiwei=i/10;
	SHT->gewei =i%10;
    SHT->DateString2[0] = SHT->shiwei + '0';
	SHT->DateString2[1] = SHT->gewei + '0';
	i=(int)((datax1-i)*10); 
	SHT->DateString2[2] ='.';
	SHT->DateString2[3] = i + '0';
	SHT->DateString2[4] = '\0';
    if(0<=i<=4)
      sht11[1] = (int)datax1;
    else
      sht11[1] = (int)(datax1+1);
}

/*************************************************************************************/
void TEM_HUM_DISP(void)
{
 SHT11 S1;
 value humi_val,temp_val;
 unsigned char error,checksum;
 error=0;
 error+=s_measure((unsigned char*) &humi_val.i,&checksum,1);
 error+=s_measure((unsigned char*) &temp_val.i,&checksum,0); 
 if(error!=0) 
  connectionreset(); 
 else
 { 
  humi_val.f=(float)humi_val.i;
  temp_val.f=(float)temp_val.i;
  calc_sth11(&humi_val.f,&temp_val.f); 
  DateToString(&S1,temp_val.f,humi_val.f);		                  
  setPosition(2,2);
  writeString(S1.DateString1);         
  setPosition(2,6);
  writeString(S1.DateString2);
 }
}
/*************************************************************************************/