This DHT11 based sensor measures both Temperature and Humidity in one package. Features include resistive humidity sensing components. It is durable, and has a fast response with great anti-interference ability. This DHT11 temperature and humidity sensor module uses a dedicated digital module and acquisition of temperature and humidity sensor technology to ensure the product with high reliability and excellent long-term stability. It is fully digitally operated so no analog-to-digital calibration is required. Perfect for DIY projects requiring temperature or humidity data.

Test Code

int DHpin = 8;
byte dat [5];

byte read_data () {
byte data;
for (int i = 0; i < 8; i ++) {
if (digitalRead (DHpin) == LOW) {
while (digitalRead (DHpin) == LOW);
// wait for 50us;
delayMicroseconds (30);
// determine the duration of the high level to determine the data is '0 'or '1';
if (digitalRead (DHpin) == HIGH)
data | = (1 << (7-i)); / / high front and low in the post;
while (digitalRead (DHpin) == HIGH); // data '1 ', wait for the next one receiver;
}
}
return data;
}

void start_test () {
digitalWrite (DHpin, LOW); // bus down, send start signal;
delay (30); // delay greater than 18ms, so DHT11 start signal can be detected;
digitalWrite (DHpin, HIGH);
delayMicroseconds (40); // Wait DHT11 response;
pinMode (DHpin, INPUT);

while (digitalRead (DHpin) == HIGH);
delayMicroseconds (80); // DHT11 a response, pulled the bus 80us;
if (digitalRead (DHpin) == LOW);
delayMicroseconds (80); // DHT11 80us after the bus pulled to start sending data;

// receives temperature and humidity data, the parity bit is not considered;
for (int i = 0; i <4; i + +)
dat [i] = read_data ();
pinMode(DHpin, OUTPUT);
// sending data once after releasing the bus, wait for the host to open the next Start signal;
digitalWrite(DHpin, HIGH);
}

void setup () {
Serial.begin (9600);
pinMode(DHpin, OUTPUT);
}

void loop () {
start_test ();
Serial.print ("Current humdity =");
Serial.print (dat [0], DEC); // display the humidity-bit integer;
Serial.print ('.');
Serial.print (dat [1], DEC); // display the humidity decimal places;
Serial.println ('%');
Serial.print ("Current temperature =");
Serial.print (dat [2], DEC); // display the temperature of integer bits;
Serial.print ('.');
Serial.print (dat [3], DEC); // display the temperature of decimal places;
Serial.println ('C');
delay (700);
}