Thaimicrotron.com : Home    
 
การใช้งาน SHT15
โมดูลวัดอุณหภูมิ และความชื้น
 
     
 
 
 
การใช้งาน SHT15 กับ PIC16F648A
  
     
  เนื่องจากในโปรแกรม ใช้ฟังก์ชั่นทางคณิตศาสตร์ #include <math.h> และมีการคำนวนแบบ floating point ทำให้ไฟล์มีขนาดใหญ่ เมื่อคอมไพล์แล้ว จะมีขนาดใหญ่กว่า 2K จึงไม่สามารถใช้กับ PIC16F628 ได้ ดังนั้นจึงต้องใช้กับ PIC ที่มี Code Memory ที่มีขนาดใหญ่ขึ้นเช่น PIC16F648A หรือ PIC16F877  
     
  ตัวอย่างโปรแกรม PIC16F648A  
  
//SHT1x Sensor temperature & Humidity
//Read sensor and diaplay to RS232
//Compiler CCS Version 3.249

#case
#include <16F648A.h>
#use delay(clock=4000000)
#fuses XT,PUT,BROWNOUT,MCLR,NOWDT,NOPROTECT,NOLVP
#use rs232(baud=9600,parity=N,xmit=PIN_B2,rcv=PIN_B1)
#include <math.h>


#define SHT1xDATA  PIN_B4
#define SHT1xSCK   PIN_B5
#define noACK 0 
#define ACK   1 

// SHT1x address=000 is currently supported 
// SHT1x command code 
                            //adr  command  r/w 
#define STATUS_REG_W 0x06   //000   0011    0 
#define STATUS_REG_R 0x07   //000   0011    1 
#define MEASURE_TEMP 0x03   //000   0001    1 
#define MEASURE_HUMI 0x05   //000   0010    1 
#define RESET        0x1E   //000   1111    0 

// constant use for SHT1x Humidity Measurement 
#define C1  -4.0 
#define C2  0.0405 
#define C3  -0.0000028 

// constant use for SHT1x Temperature Measurement 
#define D1  -40.0 
#define D2  0.01 

// constant use for SHT1x True Humidity Measurement 
#define T1  0.01 
#define T2  0.00008 

//PIC16F6X8
#define  CMCON   0x1F
#define  PORTA	 0x05
#define  PORTB	 0x06


void InitialChip(void);

//SHT1x Transmission Start condition
void SHTStart()
{
   output_high(SHT1xDATA);
   output_low(SHT1xSCK);
   output_high(SHT1xSCK);
   output_low(SHT1xDATA);
   output_low(SHT1xSCK);
   output_high(SHT1xSCK);
   output_high(SHT1xDATA);
   output_low(SHT1xSCK);

}

// SHT1x Connection Reset:
void SHTConReset() 
{ 
int i; 

   output_high(SHT1xDATA); 

   for (i=0; i<9; i++) 
   { 
      output_high(SHT1xSCK); 
      delay_us(2); 
      output_low(SHT1xSCK); 
      delay_us(2); 
   } 
   SHTStart(); 
} 

// SHT1x Address & Command Mode with address=000 
int SHTWrite(int Data) 
{ 
int i; 

   for (i=0x80;i>0;i/=2)        //shift bit for masking data
   { 
    if(i&Data)
     output_high(SHT1xDATA); 
    else  
     output_low(SHT1xDATA); 

     delay_us(2);               //Snend Clock each bit 
     output_high(SHT1xSCK); 
     delay_us(2); 
     output_low(SHT1xSCK); 
   } 

   output_float(SHT1xDATA);     //Change DATA Line to Input 
   delay_us(2); 

   output_high(SHT1xSCK);       //Clock for Acknowledge 
   delay_us(2); 

   i= input(SHT1xDATA);         //Get Acknowledge

   output_low(SHT1xSCK); 
   delay_ms(250);
   return (i);
} 

//Read data from SHT1x
long SHTRead(void) 
{ 
int i; 
long lTmp,lVal1,lVal2,lValue; 

   lVal1=0;
   lVal2=0; 

//get MSB from SHT1x 
   for (i=0; i<8; i++) 
   { 
    lVal1<<=1; 
    output_high(SHT1xSCK);          //Send Clock Hight
    lTmp = input(SHT1xDATA);        //Read Data Bit 
    //delay_us(2); 
    output_low(SHT1xSCK);           //Send Clock Low
    //delay_us(2); 

    if(lTmp) 
     lVal1|=1;                      //store in lVal1
   } 

//Acknowledge routine for Next byte
   output_low(SHT1xDATA); 
   output_high(SHT1xSCK); 
   //delay_us(2); 

   output_float(SHT1xDATA);         //Change to Input
   output_low(SHT1xSCK); 
   //delay_us(2); 

//get LSB from SHT1x 
   for (i=0; i<8; i++) 
   { 
    lVal2<<=1; 
    output_high(SHT1xSCK);          //Send Clock Hight 
    lTmp = input(SHT1xDATA);        //Read Data Bit  
    //delay_us(2); 
    output_low(SHT1xSCK);           //Send Clock Low
    //delay_us(2); 

    if(lTmp) 
      lVal2|=1;                     //store in lVal2
   } 
   

   lValue = make16(lVal1,lVal2);    //Makes a 16 bit number out of two 8 bit numbers.
   return(lValue); 
} 
// SHT1x Soft Reset 
// resets the interface, clears the status register to default values 
// wait minimum 11ms before next command 
void SHTSoftReset() 
{ 
  SHTConReset(); 
  SHTWrite(RESET); 
} 

// calculate dewpoint 
float sht1x_calc_dewpoint(float fRh,float fTemp) 
{ 
   float fDewpoint; 
   float fLogEW; 

   fLogEW = ((7.5*fTemp)/(237.3+fTemp))+log10(fRh)-1.33923; 
   fDewpoint = ((0.66077-log10(fLogEW))*(237.3))/(log10(fLogEW)-8.16077); 
   return(fDewpoint); 
} 
void InitialChip(void)
{
    setup_comparator(NC_NC_NC_NC);   //Input Digital
    set_tris_b(0B00000001);
}

// Main Program 
main() 
{ 
float fRh_lin; 
float fRh_true; 
float fTemp_true; 
float fDew_point; 

long lValue_rh; 
long lValue_temp; 
int R;

   InitialChip();
   delay_ms(200);

   SHTConReset(); 

   while (TRUE) 
   { 
     // delay >11ms before next command 
      delay_ms(12); 

      SHTStart();                                                        //@1 start transmission 
      R=SHTWrite(MEASURE_TEMP);           //@2 measure temperature 
      if(R==1)
      {
       printf("Sensor Error\n");
       delay_ms(1000);
       continue;
      }

      lValue_temp = SHTRead(); 

      // temperature calculation 
      fTemp_true = (D1+(D2*lValue_temp)); 

      // delay 11ms before next command 
      delay_ms(12); 

      // start transmission 
      SHTStart(); 

      // measure relative humidity 
      SHTWrite(MEASURE_HUMI); 
      lValue_rh = SHTRead(); 

      // relative humidity calculation 
      fRh_lin = (C1+(C2*lValue_rh)+(C3*lValue_rh*lValue_rh)); 
      fRh_true = (((fTemp_true-25)*(T1+(T2*lValue_rh)))+fRh_lin); 

      // dewpoint calculation 
      fDew_point = sht1x_calc_dewpoint(fRh_true,fTemp_true); 

      printf("T=%3.2f C\r\n",fTemp_true); 
      printf("H=%3.2f%%\r\n",fRh_true); 
      printf("Dew Point: %3.6fC \r\n\r\n",fDew_point); 
      delay_ms(1000); 
   } 
}
 
     
 
 
  การใช้งานกับ PIC16F877  
 
 
 
การใช้งาน SHT15 กับ PIC16F877
  
     
ตัวอย่างโปรแกรม PIC16F877  
     
  
//SHT1x Sensor temperature & Humidity
//Read sensor and diaplay to RS232
//Compiler CCS Version 3.249

#case
#include <16F877A.h>
#use delay(clock=4000000)
#fuses XT,PUT,BROWNOUT,NOWDT,NOPROTECT,NOLVP
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7)
#include <math.h>

#define SHT1xDATA  PIN_B4
#define SHT1xSCK   PIN_B5
#define noACK 0 
#define ACK   1 

// SHT1x address=000 is currently supported 
// SHT1x command code 
                            //adr  command  r/w 
#define STATUS_REG_W 0x06   //000   0011    0 
#define STATUS_REG_R 0x07   //000   0011    1 
#define MEASURE_TEMP 0x03   //000   0001    1 
#define MEASURE_HUMI 0x05   //000   0010    1 
#define RESET        0x1E   //000   1111    0 

// constant use for SHT1x Humidity Measurement 
#define C1  -4.0 
#define C2  0.0405 
#define C3  -0.0000028 

// constant use for SHT1x Temperature Measurement 
#define D1  -40.0 
#define D2  0.01 

// constant use for SHT1x True Humidity Measurement 
#define T1  0.01 
#define T2  0.00008 

//PIC16F6X8
#define  CMCON   0x1F
#define  PORTA	 0x05
#define  PORTB	 0x06


void InitialChip(void);

//SHT1x Transmission Start condition
void SHTStart()
{
   output_high(SHT1xDATA);
   output_low(SHT1xSCK);
   output_high(SHT1xSCK);
   output_low(SHT1xDATA);
   output_low(SHT1xSCK);
   output_high(SHT1xSCK);
   output_high(SHT1xDATA);
   output_low(SHT1xSCK);

}

// SHT1x Connection Reset:
void SHTConReset() 
{ 
int i; 

   output_high(SHT1xDATA); 

   for (i=0; i<9; i++) 
   { 
      output_high(SHT1xSCK); 
      delay_us(2); 
      output_low(SHT1xSCK); 
      delay_us(2); 
   } 
   SHTStart(); 
} 

// SHT1x Address & Command Mode with address=000 
int SHTWrite(int Data) 
{ 
int i; 

   for (i=0x80;i>0;i/=2)        //shift bit for masking data
   { 
    if(i&Data)
     output_high(SHT1xDATA); 
    else  
     output_low(SHT1xDATA); 

     delay_us(2);               //Snend Clock each bit 
     output_high(SHT1xSCK); 
     delay_us(2); 
     output_low(SHT1xSCK); 
   } 

   output_float(SHT1xDATA);     //Change DATA Line to Input 
   delay_us(2); 

   output_high(SHT1xSCK);       //Clock for Acknowledge 
   delay_us(2); 

   i= input(SHT1xDATA);         //Get Acknowledge

   output_low(SHT1xSCK); 
   delay_ms(250);
   return (i);
} 

//Read data from SHT1x
long SHTRead(void) 
{ 
int i; 
long lTmp,lVal1,lVal2,lValue; 

   lVal1=0;
   lVal2=0; 

//get MSB from SHT1x 
   for (i=0; i<8; i++) 
   { 
    lVal1<<=1; 
    output_high(SHT1xSCK);          //Send Clock Hight
    lTmp = input(SHT1xDATA);        //Read Data Bit 
    //delay_us(2); 
    output_low(SHT1xSCK);           //Send Clock Low
    //delay_us(2); 

    if(lTmp) 
     lVal1|=1;                      //store in lVal1
   } 

//Acknowledge routine for Next byte
   output_low(SHT1xDATA); 
   output_high(SHT1xSCK); 
   //delay_us(2); 

   output_float(SHT1xDATA);         //Change to Input
   output_low(SHT1xSCK); 
   //delay_us(2); 

//get LSB from SHT1x 
   for (i=0; i<8; i++) 
   { 
    lVal2<<=1; 
    output_high(SHT1xSCK);          //Send Clock Hight 
    lTmp = input(SHT1xDATA);        //Read Data Bit  
    //delay_us(2); 
    output_low(SHT1xSCK);           //Send Clock Low
    //delay_us(2); 

    if(lTmp) 
      lVal2|=1;                     //store in lVal2
   } 
   

   lValue = make16(lVal1,lVal2);    //Makes a 16 bit number out of two 8 bit numbers.
   return(lValue); 
} 
// SHT1x Soft Reset 
// resets the interface, clears the status register to default values 
// wait minimum 11ms before next command 
void SHTSoftReset() 
{ 
  SHTConReset(); 
  SHTWrite(RESET); 
} 

// calculate dewpoint 
float sht1x_calc_dewpoint(float fRh,float fTemp) 
{ 
   float fDewpoint; 
   float fLogEW; 

   fLogEW = ((7.5*fTemp)/(237.3+fTemp))+log10(fRh)-1.33923; 
   fDewpoint = ((0.66077-log10(fLogEW))*(237.3))/(log10(fLogEW)-8.16077); 
   return(fDewpoint); 
} 
void InitialChip(void)
{
    setup_comparator(NC_NC_NC_NC);   //Input Digital
    set_tris_b(0B00000000);
    set_tris_c(0B10000000);
}

// Main Program 
main() 
{ 
float fRh_lin; 
float fRh_true; 
float fTemp_true; 
float fDew_point; 

long lValue_rh; 
long lValue_temp; 
int R;

   InitialChip();
   delay_ms(200);

   SHTConReset(); 

   while (TRUE) 
   { 
     // delay >11ms before next command 
      delay_ms(12); 

      SHTStart();                                                        //@1 start transmission 
      R=SHTWrite(MEASURE_TEMP);           //@2 measure temperature 
      if(R==1)
      {
       printf("Sensor Error\n");
       delay_ms(1000);
       continue;
      }

      lValue_temp = SHTRead(); 

      // temperature calculation 
      fTemp_true = (D1+(D2*lValue_temp)); 

      // delay 11ms before next command 
      delay_ms(12); 

      // start transmission 
      SHTStart(); 

      // measure relative humidity 
      SHTWrite(MEASURE_HUMI); 
      lValue_rh = SHTRead(); 

      // relative humidity calculation 
      fRh_lin = (C1+(C2*lValue_rh)+(C3*lValue_rh*lValue_rh)); 
      fRh_true = (((fTemp_true-25)*(T1+(T2*lValue_rh)))+fRh_lin); 

      // dewpoint calculation 
      fDew_point = sht1x_calc_dewpoint(fRh_true,fTemp_true); 

      printf("T=%3.2f C\r\n",fTemp_true); 
      printf("H=%3.2f%%\r\n",fRh_true); 
      printf("Dew Point: %3.6fC \r\n\r\n",fDew_point); 
      delay_ms(1000); 
   } 
}
 
 
 
   
  ผลการทดลองของทั้งสองโปรแกรม ผ่าน Hyperterminal Baudrate 9600,n,8,1  
  
T=23.98 C
H=59.39%
Dew Point: -17.857664C

T=23.98 C
H=59.39%
Dew Point: -17.857664C

T=23.98 C
H=59.39%
Dew Point: -17.857664C

 
     
  จะแสดงผลทุกๆ 1 วินาที  
  หากไม่ได้ต่อ sensor จะแสดงว่า"Sensor Error"  
 
SMITDH EMSOMBATศมิทธิ์ เอมสมบัติ