STC12C5A60S2的DHT22以及MQ-2的1602显示程序 -

#include"main.h"
sbit DHT22_DATA = P2^0;
unsigned char a,b,c,d,check=1; //8bit温度整数数据+8bit温度小数数据+8bit湿度整数数+8bit湿度小数数据+8bit校验和
unsigned int R,T;
unsigned char n;
void delay500us(void) //误差 -0.054253472222us
{
unsigned char a,b;
for(b=251;b>0;b--)
for(a=4;a>0;a--);
_nop_(); //if Keil,require use intrins.h
}
void delay20us(void) //误差 -0.016637731481us
{
unsigned char a,b;
for(b=1;b>0;b--)
for(a=52;a>0;a--);
_nop_(); //if Keil,require use intrins.h
}
char Read_Byte()
{
char temp,tmp;
unsigned char i;
for(i=0;i<8;i++)
{
// delay20us();
n = 2;
while((!DHT22_DATA)&&n++); //等待50us间隔低电平响应结束
if(n == 1) return 0;
delay20us();delay20us(); //26-28us高电平为‘0’，70us高电平为‘1’
tmp = 0;
if(DHT22_DATA) tmp = 1;
n = 2;
while(DHT22_DATA&&n++); //若位为1,等待高电平结束
if(n == 1) return 0;
temp <<= 1;
temp |= tmp;
}
return temp;
}
unsigned char DHT22_Read()
{
DHT22_DATA = 0;
delay500us(); //拉低500us
DHT22_DATA = 1;
delay20us();delay20us(); //延时20-40us等待响应信号
DHT22_DATA = 1;
if(!DHT22_DATA)
{
n = 2;
while((!DHT22_DATA)&&n++); //等待80us低电平响应结束
if(n == 1) return 0;
delay20us();delay20us();delay20us();
n = 2;
while(DHT22_DATA&&n++); //等待80s高电平等待结束
if(n == 1) return 0;
a = Read_Byte();
b = Read_Byte();
c = Read_Byte();
d = Read_Byte();
check = Read_Byte();
DHT22_DATA = 1;
if(check != a+b+c+d) return 0;
}
R = a*256+b;
T = c*256+d;
return 1;
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