//这是我用成功的
/*************定义接口********************
P2.6------SCK P2.7------DATA
*****************************************/
#include <AT89x51.h>
#include <intrins.h>
#include <math.h> //Keil library
#include <stdio.h> //Keil library
/******定义函数****************/
#define uchar unsigned char
#define uint unsigned int
void delay_n10us(uint n); //延时函数
/*--------------------------------------
;模块名称:delay_n10us();
;功 能:延时函数，延时约n个10us
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.1(函数版本Function Version)
;修改日期:2008.08.26
;修改说明:修改为较精确的延时函数,"_nop_()"延时1us@12M晶振
;-------------------------------------*/
void delay_n10us(uint n) //延时n个10us@12M晶振
{
uint i;
for(i=n;i>0;i--)
{
_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();
}
}
//*********************第二部分DHT90设置 START****************************************
sbit SCK = P2^6; //定义通讯时钟端口
sbit DATA = P2^7; //定义通讯数据端口
typedef union
{ unsigned int i; //定义了两个共用体
float f;
} value;
enum {TEMP,HUMI}; //TEMP=0,HUMI=1
#define noACK 0 //用于判断是否结束通讯
#define ACK 1 //结束数据传输
//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
/****************定义函数****************/
void s_transstart(void); //启动传输函数
void s_connectionreset(void); //连接复位函数
char s_write_byte(unsigned char value);//DHT90写函数
char s_read_byte(unsigned char ack); //DHT90读函数
char s_measure(unsigned char *p_value, unsigned char *p_checksum, unsigned char mode);//测量温湿度函数
void calc_dht90(float *p_humidity ,float *p_temperature);//温湿度补偿
/*--------------------------------------
;模块名称:s_transstart();
;功 能:启动传输函数
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.0(函数版本Function Version)
;修改日期:--
;修改说明:--
;-------------------------------------*/
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_();_nop_();_nop_();
SCK=1;
_nop_();
DATA=1;
_nop_();
SCK=0;
}
/*--------------------------------------
;模块名称:s_connectionreset();
;功 能:连接复位函数
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.0(函数版本Function Version)
;修改日期:--
;修改说明:--
;-------------------------------------*/
void s_connectionreset(void)
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
// _____________________________________________________ ________
// DATA: |_______|
// _ _ _ _ _ _ _ _ _ ___ ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
{
unsigned char i;
DATA=1; SCK=0; //Initial state
for(i=0;i<9;i++) //9 SCK cycles
{
SCK=1;
SCK=0;
}
s_transstart(); //transmission start
}
/*--------------------------------------
;模块名称:s_write_byte();
;功 能:DHT90写函数
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.0(函数版本Function Version)
;修改日期:--
;修改说明:--
;-------------------------------------*/
char s_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) //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. 3 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
}
/*--------------------------------------
;模块名称:s_read_byte();
;功 能:DHT90读函数
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.0(函数版本Function Version)
;修改日期:--
;修改说明:--
;-------------------------------------*/
char s_read_byte(unsigned char ack)
// reads a byte form the Sensibus and gives an acknowledge in case of "ack=1"
{
unsigned char 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. 3 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. 3 us
SCK=1; //clk #9 for ack
_nop_();_nop_();_nop_(); //pulswith approx. 3 us
SCK=0;
_nop_();_nop_();_nop_(); //pulswith approx. 3 us
DATA=1; //release DATA-line
return val;
}
/*--------------------------------------
;模块名称:s_measure();
;功 能:测量温湿度函数
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.0(函数版本Function Version)
;修改日期:--
;修改说明:--
;-------------------------------------*/
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;
s_transstart(); //transmission start
switch(mode){ //send command to sensor
case TEMP : error+=s_write_byte(MEASURE_TEMP); break;
case HUMI : error+=s_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) =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
return error;
}
/*--------------------------------------
;模块名称:calc_dht90();
;功 能:温湿度补偿函数
;占用资源:--
;参数说明:--
;创建日期:2008.08.15
;版 本:FV1.0(函数版本Function Version)
;修改日期:--
;修改说明:--
;-------------------------------------*/
void calc_dht90(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]
}
//*********************第二部分DHT90设置 END****************************************
//*********主函数*****************
void dht90(void)
{
value humi_val,temp_val;
unsigned char error,checksum;
unsigned int wendu,shidu;
s_connectionreset();
//*********初始化温度显示区*********
LCD_disp_str(2,1,"TTT.TC");
//*********初始化湿度显示区*********
LCD_disp_str(2,2,"RRR.R%");
delay_n10us(20000); //延时0.2s
while(1)
{ error=0;
error+=s_measure((unsigned char*) &humi_val.i,&checksum,HUMI); //measure humidity
error+=s_measure((unsigned char*) &temp_val.i,&checksum,TEMP); //measure temperature
if(error!=0) s_connectionreset(); //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
calc_dht90(&humi_val.f,&temp_val.f); //calculate humidity, temperature
wendu=10*temp_val.f;
LCD_disp_char(2,1,wendu/1000+'0'); //显示温度百位
LCD_disp_char(3,1,(wendu%1000)/100+'0'); //显示温度十位
LCD_disp_char(4,1,(wendu%100)/10+'0'); //显示温度个位
LCD_disp_char(6,1,(wendu%10)+'0'); //显示温度小数点后第一位
shidu=10*humi_val.f;
LCD_disp_char(2,2,shidu/1000+'0'); //显示湿度百位
LCD_disp_char(3,2,(shidu%1000)/100+'0'); //显示湿度十位
LCD_disp_char(4,2,(shidu%100)/10+'0'); //显示湿度个位
LCD_disp_char(6,2,(shidu%10)+'0'); //显示湿度小数点后第一位
}
//----------wait approx. 0.8s to avoid heating up SHTxx------------------------------
delay_n10us(80000); //延时约0.8s
}
}