dht11.c

#include "dht11.h"
#include "delay.h"

    
//Rest dht11
void DHT11_Rst(void)	   
{                 
	DHT11_IO_OUT(); 	//SET OUTPUT
  DHT11_DQ_OUT=0; 	//pull down DQ
  delay_ms(20);    	//Pull down 18ms
  DHT11_DQ_OUT=1; 	//DQ=1 
	delay_us(30);     	//pull up 20~40us
}
//wait DHT11
//1:no dht11
//0:exist
u8 DHT11_Check(void) 	   
{   
	u8 retry=0;
	DHT11_IO_IN();//SET INPUT	 
    while (DHT11_DQ_IN&&retry<100)//DHT11 pull down 40~80us
	{
		retry++;
		delay_us(1);
	};	 
	if(retry>=100)return 1;
	else retry=0;
    while (!DHT11_DQ_IN&&retry<100)//DHT11 pull up 40~80us
	{
		retry++;
		delay_us(1);
	};
	if(retry>=100)return 1;	    
	return 0;
}
//read one bit

u8 DHT11_Read_Bit(void) 			 
{
 	u8 retry=0;
	while(DHT11_DQ_IN&&retry<100)//wait low level
	{
		retry++;
		delay_us(1);
	}
	retry=0;
	while(!DHT11_DQ_IN&&retry<100)//wiat high level
	{
		retry++;
		delay_us(1);
	}
	delay_us(40);//wait 40us
	if(DHT11_DQ_IN)return 1;
	else return 0;		   
}
//read one byte
//
u8 DHT11_Read_Byte(void)    
{        
    u8 i,dat;
    dat=0;
	for (i=0;i<8;i++) 
	{
   		dat<<=1; 
	    dat|=DHT11_Read_Bit();
    }						    
    return dat;
}

u8 DHT11_Read_Data(u8 *temp,u8 *humi)    
{        
 	u8 buf[5];
	u8 i;
	DHT11_Rst();
	if(DHT11_Check()==0)
	{
		for(i=0;i<5;i++)//read 40 bits data
		{
			buf[i]=DHT11_Read_Byte();
		}
		if((buf[0]+buf[1]+buf[2]+buf[3])==buf[4])
		{
			*humi=buf[0];
			*temp=buf[2];
		}
	}else return 1;
	return 0;	    
}
//Init DHT11   	 
u8 DHT11_Init(void)
{
	GPIO_InitTypeDef  GPIO_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOG, ENABLE);//ENABLE CLOCK

  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 ;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;//50MHz
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOG, &GPIO_InitStructure);
	DHT11_Rst();
	return DHT11_Check();
}