Arduino

/**********************************
 * name: Humiture Detection
 * function:you can see the current value of humidity and temperature displayed on the I2C LCD1602.
 *************************************/
 #include <dht.h>
 #include <LiquidCrystal_I2C.h>
 #include <Wire.h>
 LiquidCrystal_I2C lcd(0x27, 16, 2); //set the LCD address to 0x27 for a 16 chars and 2 lines display
 dht DHT; //Create a variable type of dht
 const int DHT11_PIN = 7; 

 void setup()
 {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
 }

 void loop()
 {
  //Read data
  //Serial.print("DHT11: ");
  D: int chk = DHT.read11(DHT11_PIN); //read the value returned from sensor
  switch (chk)
  {
    case DHTLIB_OK:
        //Serial.print("OK!");
        break;
    case DHTLIB_ERROR_CHECKSUM:
        //Serial.print("Checksum error, \t");
        break;
    case DHTLIB_ERROR_TIMEOUT:
        goto D;
        //Seiral.print("Time out error, \t");
        break;
    default:
        //Serial.print("Unknown error, \t");
        break;
  }

  //Display data
  lcd.setCursor(0, 0);
  lcd.print("Tem:");
  //Serail.print("Tem:");
  lcd.print(DHT.temperature, 1);
  //Serial.print(DHT.Temperature, 1);
  lcd.print(char(223));
  lcd.print("C");
  lcd.setCursor(0, 1);
  lcd.print("Hum:");
  lcd.print(DHT.humidity, 1);
  //Serial.println(DHT.humidity, 1);
  lcd.print(" %");
  //Serial.print(" %");
  delay(200); //wait a while
 }

树莓派

C

#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#define MAXTIMINGS 85
#define DHTPIN 0

int dht11_dat[5] = {0,0,0,0,0};
void read_dht11_dat()
{
    uint8_t laststate = HIGH;
    uint8_t counter = 0;
    uint8_t j = 0, i;
    float f; // fahrenheit
    dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0;
    // pull pin down for 18 milliseconds
    pinMode(DHTPIN, OUTPUT);
    digitalWrite(DHTPIN, LOW);
    delay(18);
    // then pull it up for 40 microsencods
    digitalWrite(DHTPIN, HIGH);
    delayMicroseconds(40);
    // prepare to read the pin
    pinMode(DHTPIN, INPUT);
    // detect change and read data
    for (i = 0; i < MAXTIMINGS; i++){
        counter = 0;
        while (digitalRead(DHTPIN) == laststate){
            counter ++;
            delayMicroseconds(1);
            if (counter == 255){
                break;             
            }
        }
        laststate = digitalRead(DHTPIN);
        if (counter == 255) break;
        // ingnore first 3 transitions
        if ((i >= 4) && (i%2 == 0)){
            // shove each bit into the storage bytes
            dht11_dat[j/8] <<= 1;
            if (counter > 16)
                    dht11_dat[j/8] |= 1;
            j ++;
        }
    }
    // check we read 40 bits (8bits x 5) + verify checksum in the last byte
    // print it out if data is good
    if ((j >= 40) &&
            (dht11_dat[4] == ((dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF)) ){
        f = dht11_dat[2] * 9. / 5. + 32;
        printf("Humidity = %d.%d %% Temperature = %d.%d *C (%.1f *F)\n", 
                        dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], f);
    }
    else
    {
        printf("Data not good, skip\n");
    }
}

int main(void)
{
    printf("Rasbperry Pi wiringPi DHT11 Temperature test program\n");
    if (wiringPiSetup() == -1)
            exit(1);
    while(1)
    {
        read_dht11_dat();
        delay(1000); // wait 1 sec to refresh
    }
    return 0;
}

Python

import RPi.GPIO as GPIO
import time

DHTPIN = 17
GPIO.setmode(GPIO.BCM)
MAX_UNCHANGE_COUNT = 100
STATE_INIT_PULL_DOWN = 1
STATE_INIT_PULL_UP = 2
STATE_DATA_FIRST_PULL_DOWN = 3
STATE_DATA_PULL_UP = 4
STATE_DATA_PULL_DOWN = 5

def read_dht11_dat():
    GPIO.setup(DHTPIN, GPIO.OUT)
    GPIO.output(DHTPIN, GPIO.HIGH)
    time.sleep(0.05)
    GPIO.output(DHTPIN, GPIO.LOW)
    time.sleep(0.02)
    GPIO.setup(DHTPIN, GPIO.IN, GPIO.PUD_UP)
    
    unchanged_count = 0
    last = -1
    data = []
    while True:
        current = GPIO.input(DHTPIN)
        data.append(current)
        if last != current:
            unchanged_count = 0
            last = current
        else:
            unchanged_count += 1
            if unchanged_count > MAX_UNCHANGE_COUNT:
                break

    state = STATE_INIT_PULL_DOWN 
    lengths = []
    current_length  = 0
    for current in data:
        current_length += 1

        if state == STATE_INIT_PULL_DOWN:
            if current == GPIO.LOW:
                state = STATE_INIT_PULL_UP
            else:
                continue
        if state == STATE_INIT_PULL_UP:
            if current == GPIO.HIGH:
                state = STATE_DATA_FIRST_PULL_DOWN
            else:
                continue
        if state == STATE_DATA_FIRST_PULL_DOWN:
            if current == GPIO.LOW:
                state = STATE_DATA_PULL_UP
            else:
                continue
        if state == STATE_DATA_PULL_UP:
            if current == GPIO.HIGH:
                current_length = 0
                state = STATE_DATA_PULL_DOWN
            else:
                continue
        if state == STATE_DATA_PULL_DOWN:
            if current == GPIO.LOW:
                lengths.append(current_length)
                state = STATE_DATA_PULL_UP
            else:
                continue

    if len(lengths) != 40:
        print("Data not good, skip")
        return False

    shortest_pull_up = min(lengths)
    longest_pull_up = max(lengths)
    halfway = (longest_pull_up + shortest_pull_up) / 2
    bits = []
    the_bytes = []
    byte = 0

    for length in lengths:
        bit = 0
        if length > halfway:
            bit = 1
        bits.append(bit)
    print("bits: %s, length: %d" % (bits, len(bits)))
    for i in range(0, len(bits)):
        byte = byte << 1
        if (bits[i]):
            byte = byte | 1
        else:
            byte = byte | 0
        if ((i + 1) % 8 == 0):
            the_bytes.append(byte)
            byte = 0
    print(the_bytes)
    checksum = (the_bytes[0] + the_bytes[1] + the_bytes[2] + the_bytes[3]) & 0xFF
    if the_bytes[4] != checksum:
        print("Data not good, skip")
        return False

    return the_bytes[0], the_bytes[2]

def main():
    print("Rasbperry Pi wiringPi DHT11 Temperature test program\n")
    while True:
        result = read_dht11_dat()
        if result:
            humidity,temperature = result
            print("Humidity: %s %%, Temperature: %s C" % (humidity, temperature))
        time.sleep(1)

def destroy():
    GPIO.cleanup()


if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        destroy()