温湿度检测程序

//串行控制sht75

#include

//#include

#include

#include

sbit SCL = P1 ^ 6 ; //时钟

sbit SDA = P1 ^ 7 ; //数据

#define noACK 0

#define ACK 1 //noACK和ACK有无响应

#define spect_TEMP 99 //温度测量范围0-99

#define spect_HUMI 100 //湿度测量范围0-100

bit Ack; //应答标志

enum {TEMP,HUMI};

typedef union

{

unsigned int i;

float f;

}value;

//命令

// 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_MUMI 0x05 //000 0010 1

#define RESET 0x1e //000 1111 0

void start(void);

unsigned char writeByte(unsigned char value);

unsigned char RevByte(unsigned char c);

unsigned char S_measure(unsigned char *p_value,unsigned char *p_checksum,unsigned char mode);

unsigned char S_softreset(void);

unsigned char writeStatusreg(void);

void Calc_sht75(float *p_humidity,float *p_tempature);

value humi_data,temp_data;

//开始传输命令

void start(void)

{

SCL=1;

SDA=1;

SCL=1;

SDA=0;

_nop_();

SCL=0;

_nop_();

SCL=1;

SDA=1;

_nop_();

SCL=0;

SDA=0;

_nop_();

}

//写入一个字节

unsigned char writeByte(unsigned char value) {

unsigned char i,error=0;

for(i=0;i<8;i++)

{

if((value<

SDA=1;

else SDA=0;

_nop_();

SCL=1;

_nop_();

_nop_();

_nop_();

_nop_();

_nop_();

SCL=0;

}

_nop_();

_nop_();

SDA=1;

_nop_();

_nop_();

SCL=1;

_nop_();

_nop_();

_nop_();

if(SDA==1)

{

error=1;

return error;

}

else

{Ack=1;}

SCL=0;

_nop_();

_nop_();

return error;

}

//接收函数

unsigned char RevByte(unsigned char c) {

unsigned char retc;

unsigned char BitCnt;

retc=0;

SDA=1;

for(BitCnt=0;BitCnt<8;BitCnt++)

{

_nop_();

SCL=0; //时钟低位，准备接受

_nop_();

_nop_();

_nop_();

_nop_();

_nop_();

SCL=1; //时钟高位，数据有效

_nop_();

_nop_();

retc=retc<<1;//左移

if(SDA==1)

retc=retc+1;

_nop_();

_nop_();

}

SCL=0;

_nop_();

_nop_();

if(c==0)SDA=0;//应答信号

else SDA=1;

_nop_();

_nop_();

SCL=1;

_nop_();

_nop_();

_nop_();

_nop_();

_nop_();

SCL=0;

_nop_();

_nop_();

return(retc);

}

//启动温湿度测量，返回值，校验

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

{

unsigned char error=0;

unsigned long i;

start();

switch(mode)

{

case TEMP:error+=writeByte(MEASURE_TEMP);break;

case HUMI:error+=writeByte(MEASURE_MUMI);break;

default:break;

}

for(i=0;i<300000;i++)

if(SDA==0) break; //等结果

if(SDA==1) error+=1;//超时

*(p_value)=RevByte(ACK);//读MSB

*(p_value+1)=RevByte(ACK);//读LSB

*p_checksum=RevByte(noACK);

return error;

}

//软复位SHT75，错误error返回1，否则0

unsigned char S_softreset(void)

{

unsigned char error=0;

start();

error+=writeByte(RESET);

writeStatusreg();

return error;//传感器无反应返回1

}

//SHT75状态寄存器写命令，错误error返回1，否则0 unsigned char writeStatusreg(void)

{

unsigned char error=0;

start();

error+=writeByte(STATUS_REG_W);

error+=writeByte(0x00);

return error;

}

//温湿度数据转换子函数

void Calc_sth75(float *p_humidity,float *p_temperature) {

const float C1=-4.0;

const float C2=0.0405;

const float C3=-0.0000028;

const float T1=0.01;

const float T2=0.00008;

float rh=*p_humidity;

float t=*p_temperature;

float rh_lin;

float rh_true;

float t_C;

t_C=t*0.01-40;

rh_lin=C3*rh*rh+C2*rh+C1;

rh_true=(t_C-25)*(T1+T2*rh)+rh_lin;

if(rh_true>100)rh_true=100;

if(rh_true<0.01)rh_true=0.1;

*p_temperature=t_C;

*p_humidity=rh_true;

}

void initT2(void)

{

SCON=0x50;

PCON=0x80;

RCLK=1;

TCLK=1;

RCAP2H=0xff;

RCAP2L=0xfd;

TR2=1;

}

void main()

{

unsigned char error=0;

unsigned char checksum;

initT2();

start();

writeByte(RESET);

while(1);

{

error+=S_measure((unsigned char *)&humi_data.i,(unsigned char *)&checksum,HUMI);

error+=S_measure((unsigned char *)&temp_data.i,(unsigned char *)&checksum,TEMP);

if(!error)

{

humi_data.f=(float)humi_data.i;

temp_data.f=(float)temp_data.i;

Calc_sth75(&humi_data.f,&temp_data.f);

putchar((unsigned char)(&humi_data.f));

putchar((unsigned char)(&temp_data.f));

}

}

}