Arduino下读取DHT22温湿度（不使用第三方库）

代码如下：

#include <inttypes.h>
/*
* LED
*/
unsigned int LED = 13;
/*
* DHT22配置程序
*/
unsigned int DHT_PIN = 7;

#define DHT_OK      1
#define DHT_ERR_CHECK 0
#define DHT_ERR_TIMEOUT -1
float humidity;
float temperature;
unsigned char DHT_read()
{
// BUFFER TO RECEIVE
unsigned char bits[5] = {0,0,0,0,0};
unsigned char cnt = 7;
unsigned char idx = 0;
unsigned char sum;

// REQUEST SAMPLE
pinMode(DHT_PIN, OUTPUT);
digitalWrite(DHT_PIN, LOW);
delay(18);
digitalWrite(DHT_PIN, HIGH);
delayMicroseconds(40);
pinMode(DHT_PIN, INPUT);

// ACKNOWLEDGE or TIMEOUT
unsigned int count = 10000;
while(digitalRead(DHT_PIN) == LOW)
if (count-- == 0) return DHT_ERR_TIMEOUT;

count = 10000;
while(digitalRead(DHT_PIN) == HIGH)
if (count-- == 0) return DHT_ERR_TIMEOUT;

// READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
for (int i=0; i<40; i++)
{
count = 10000;
while(digitalRead(DHT_PIN) == LOW)
if (count-- == 0) return DHT_ERR_TIMEOUT;

unsigned long t = micros();

count = 10000;
while(digitalRead(DHT_PIN) == HIGH)
if (count-- == 0) return DHT_ERR_TIMEOUT;

if ((micros() - t) > 40) bits[idx] |= (1 << cnt);
if (cnt == 0)   // next byte?
{
cnt = 7;    // restart at MSB
idx++;      // next byte!
}
else cnt--;
}

sum = bits[0]+bits[1]+bits[2]+bits[3];
if(bits[4] != sum) return DHT_ERR_CHECK;

humidity = (float)((bits[0] << 8)+bits[1])/10;
temperature = (float)((bits[2] << 8)+bits[3])/10;

return DHT_OK;
}

void setup() {
pinMode(13,OUTPUT);//指示灯
pinMode(DHT_PIN,INPUT);
digitalWrite(DHT_PIN, HIGH);
}
void loop() {
DHT_read();
Serial.print("temperature:");
Serial.println(temperature);
Serial.println("============end===============");
delay(1000);
digitalWrite(LED,HIGH);
delay(925); //Delay
digitalWrite(LED,LOW);
delay(925); //Delay
}

DHT22数据手册：http://www.waveshare.net/w/upload/b/be/AM2302_V1.1.pdf