DHTPi

#include<wiringPi.h>
#include<stdio.h>

#define HIGH_TIME 32

typedef unsigned long uint32;

int pinnumber = 14;
int TMPz, TMPf, RHz, RHf;

int readdata(void)//注：当前小数部分用于以后扩展,现读出为0。一次完整的数据传输为40bit，高位先出。
{
	uint32 JYW;
	int i;
	uint32 data = 0;
	
	pinMode(pinnumber, OUTPUT);
	digitalWrite(pinnumber, HIGH);
	delay(2000);
	
	pinMode(pinnumber, OUTPUT);
	digitalWrite(pinnumber, LOW);
	delay(25);//主机把总线拉低必须大于18毫秒，保证DHT11能检测到起始信号
	digitalWrite(pinnumber, HIGH);
	pinMode(pinnumber, INPUT);
	delayMicroseconds(27);//延时等待20-40微秒，开始读取信号
	
	if(digitalRead(pinnumber)==0)
	{
		while(!digitalRead(pinnumber));
		for(i=0;i<32;i++)
		{
			while(digitalRead(pinnumber));
			while(!digitalRead(pinnumber));
			delayMicroseconds(HIGH_TIME);
			
			data*= 2;//对二进制数进行左移位操作
			if(digitalRead(pinnumber))
			{
				data++;//读取数据为1，存储在data中
			}			
		}
		for(i=0;i<8;i++)
		{
			while(digitalRead(pinnumber));
			while(!digitalRead(pinnumber));
			delayMicroseconds(HIGH_TIME);
			
			JYW*= 2;
			if(digitalRead(pinnumber))
			{
				JYW++;
			}
			
		}
		TMPz = (data>>8)&0xff;
		TMPf = data&0xff;
		RHz  = (data>>24)&0xff;
		RHf  = (data>>16)&0xff;
		JYW  = JYW&0xff;
		if(JYW == (TMPz + TMPf + RHz + RHf))
		{
			return 1;
		}
		else
		{
			return 0;
		}
		
	}
	else
	{
		return 0;
	}
}

int main(void)
{
	wiringPiSetup();	
	while(1)
	{
		if(readdata())
		{
			printf("RH:%d.%d%%\n",RHz,RHf);
			printf("TMP:%d.%d°C\n",TMPz,TMPf);
		}
		else
		{
			printf("Error.\n");
		}
	}
	return 0;
}