温湿度传感器---DHT11

一、DHT11简介

DHT11是一款有已校准数字信号输出的温湿度传感器，传感器包括一个电阻式感湿元件和一个NTC测温元件。

pin	名称	注释
1	VDD	供电 3－5.5V DC
2	DATA	串行数据，单总线
3	NC	空脚，请悬空
4	GND	接地，电源负极

二、DHT11模块特点

1. 可以检测周围环境的湿度和温度。

2. 湿度测量范围：20% - 95%（0 度-50 度范围）湿度测量误差：+-5%。
3. 温度测量范围：0 度 - 50 度温度测量误差：+/-2 度。

4. 工作电压3.3V - 5V。

5. 输出形式数字输出。

6. 单线制串行接口。

三、DHT11原理图

四、程序

#include 
#include  

typedef unsigned char  U8;       /* defined for unsigned 8-bits integer variable   */
typedef signed   char  S8;       /* defined for signed 8-bits integer variable	   */
typedef unsigned int   U16;      /* defined for unsigned 16-bits integer variable  */
typedef signed   int   S16;      /* defined for signed 16-bits integer variable    */
typedef unsigned long  U32;      /* defined for unsigned 32-bits integer variable  */
typedef signed   long  S32;      /* defined for signed 32-bits integer variable    */
typedef float          F32;      /* single precision floating point variable  32   */
typedef double         F64;      /* double precision floating point variable  64   */

#define uchar unsigned char
#define uint  unsigned int
#define Data_0_time 4

sbit  P2_0  = P2^0 ;

U8  U8FLAG,k;
U8  U8count,U8temp;
U8  U8T_data_H,U8T_data_L,U8RH_data_H,U8RH_data_L,U8checkdata;
U8  U8T_data_H_temp,U8T_data_L_temp,U8RH_data_H_temp,U8RH_data_L_temp,U8checkdata_temp;
U8  U8comdata;
U8  outdata[5]; 
U8  indata[5];
U8  count, count_r = 0;
U8  str[5]={"RS232"};
U16 U16temp1,U16temp2;

void SendData(U8 *a)
{
    outdata[0] = a[0]; 
    outdata[1] = a[1];
    outdata[2] = a[2];
    outdata[3] = a[3];
    outdata[4] = a[4];
    count      = 1;
    SBUF       = outdata[0];
}

void Delay(U16 j)
{
    U8 i;
    for(; j > 0; j--)
    { 	
        for(i = 0; i < 27; i++);
    }
}

void Delay_10us(void)
{
    U8 i;
    i--;
    i--;
    i--;
    i--;
    i--;
    i--;
}
	
void COM(void)
{
    U8 i;
    for(i = 0; i < 8; i++)	   
    {
        U8FLAG = 2;	
        while((!P2_0) && U8FLAG++);
        Delay_10us();
        Delay_10us();
        Delay_10us();
        U8temp = 0;
        if(P2_0)U8temp = 1;
        U8FLAG = 2;
        while((P2_0) && U8FLAG++);
	  
        if(U8FLAG == 1)break;

        U8comdata<<=1;
        U8comdata|=U8temp;        //0
    }
}

void RH(void)
{
    P2_0 = 0;
    Delay(180);
    P2_0 = 1;

    Delay_10us();
    Delay_10us();
    Delay_10us();
    Delay_10us();

    P2_0 = 1;
  
    if(!P2_0)		 //T !	  
    {
        U8FLAG = 2;
 
        while((!P2_0) && U8FLAG++);
        U8FLAG = 2;

        while((P2_0) && U8FLAG++);

        COM();
        U8RH_data_H_temp = U8comdata;
        COM();
        U8RH_data_L_temp = U8comdata;
        COM();
        U8T_data_H_temp  = U8comdata;
        COM();
        U8T_data_L_temp  = U8comdata;
        COM();
        U8checkdata_temp = U8comdata;
        P2_0 = 1;

        U8temp = (U8T_data_H_temp + U8T_data_L_temp + U8RH_data_H_temp + U8RH_data_L_temp);
        if(U8temp == U8checkdata_temp)
        {
            U8RH_data_H = U8RH_data_H_temp;
            U8RH_data_L = U8RH_data_L_temp;
            U8T_data_H  = U8T_data_H_temp;
            U8T_data_L  = U8T_data_L_temp;
            U8checkdata = U8checkdata_temp;
        }
    }
}

void main()
{
	//uchar str[6]={"RS232"};

	TMOD = 0x20;
	TH1  = 253;
	TL1  = 253;
	TR1  = 1;
	SCON = 0x50;  
	ES   = 1;
	EA   = 1;
	TI   = 0;
	RI   = 0;
	SendData(str);
	Delay(1);
	while(1)
	{
	   RH();

	   str[0] = U8RH_data_H;
	   str[1] = U8RH_data_L;
	   str[2] = U8T_data_H;
	   str[3] = U8T_data_L;
	   str[4] = U8checkdata;
	   SendData(str);

	   Delay(20000);
	}
}

void RSINTR() interrupt 4 using 2
{
    U8 InPut3;
    if(TI == 1)
    {
        TI = 0;
        if(count != 5)
        {
            SBUF = outdata[count];
            count++;
        }
    }

    if(RI == 1)	  
    {	
        InPut3 = SBUF;
        indata[count_r] = InPut3;
        count_r++;
        RI = 0;								 
        if(count_r == 5)
        {
            count_r = 0;
            str[0]  = indata[0];
            str[1]  = indata[1];
            str[2]  = indata[2];
            str[3]  = indata[3];
            str[4]  = indata[4];
            P0 = 0;
        }
    }
}