DHT 11/DHT22 Temp/Humidity Sensors

The DHT22 (also known as AM2302) is a more accurate and versatile temperature and humidity sensor compared to the DHT11, offering a wider temperature and humidity range, better accuracy, and a wider temperature range, but at a higher cost. 

DHT-11 comes in 3-pin and 4 pin versions

#include <DHT11.h>

#define DHT11_PIN 2

void setup(){

  Serial.begin(9600);

}

void loop(){

int chk DHT.read(DHT11_PIN);

Serial.println("temp:");

Serial.print(DHT.temperature);

Serial.print(" humi:");

Serial.println(DHT.humidity);

delay(1000);

}

#include <Wire.h>

#include <LiquidCrystal_I2C.h>// Liquid Crystal by Arduino, Adafruit

#include <DHT22.h> //DHT22 library by dvarrel

// Set the LCD address to 0x27 for a 16 chars and 2 line display

LiquidCrystal_I2C lcd(0x27, 16, 2);

//Connect to 5V, GND, SDA to A4 , SCL to A5

#define pinDATA 2

//Connect DHT22 to +5V, GND, and Data to Pin 2

DHT22 dht22(pinDATA); //define pin data

void setup()

{

 // Initialize the LCD

 lcd.begin();

 lcd.backlight();

 Serial.begin(9600); //1bit=10µs

 Serial.println("\ntest capteur DTH22");

}

void loop()

{

 float t = dht22.getTemperature();

 float h = dht22.getHumidity();

 if (dht22.getLastError() != dht22.OK) {

   Serial.print("last error :");

   Serial.println(dht22.getLastError());

 }

 Serial.print("h=");Serial.print(h,1);Serial.print("\t");

 Serial.print("t=");Serial.println(t,1);

 delay(2000); //Collecting period should be : >1.7 second

 lcd.clear();

 // Display humidity on line 0

 lcd.setCursor(0, 0);          // First row

 lcd.print("Humidity= ");

 lcd.print(h);

 // Display temperature on line 1

 lcd.setCursor(0, 1);          // Second row

 lcd.print("Temperature= ");

 lcd.print(t);

 delay(5000); // Wait 5 seconds

}

#define motorPin 9

//------------------------------

#include <DHT22.h>

#define pinDATA 3 // Digital pin D3

DHT22 dht22(pinDATA);

//-----------------------------------

#include <Wire.h>

#include <Adafruit_GFX.h>

#include <Adafruit_SH110X.h>

// I2C address for most SH1106 displays

#define I2C_ADDRESS 0x3C

// Create display object (128x64 SH1106)

Adafruit_SH1106G display(128, 64, &Wire);

#define SCREEN_WIDTH 128

#define SCREEN_HEIGHT 64

// Most 0.96" OLEDs are address 0x3C. If yours is 0x3D, change it.

#define OLED_ADDR 0x3C

#include <WiFi.h>

#include "secrets.h"

#include "ThingSpeak.h" // always include thingspeak header file after other header files and custom macros

char ssid[] = SECRET_SSID;   // your network SSID (name)

char pass[] = SECRET_PASS;   // your network password

int keyIndex = 0;            // your network key Index number (needed only for WEP)

WiFiClient  client;

unsigned long myChannelNumber = SECRET_CH_ID;

const char * myWriteAPIKey = SECRET_WRITE_APIKEY;

// Initialize our values

int number1 = 20;

int number2 = 20;

int number3 = 20;

String myStatus = "";

void setup() {

 Serial.begin(115200);  //Initialize serial

 Serial.println("\ntest capteur DTH22");

 while (!Serial) {

   ; // wait for serial port to connect. Needed for Leonardo native USB port only

 }

 WiFi.mode(WIFI_STA);  

 ThingSpeak.begin(client);  // Initialize ThingSpeak

  Wire.begin();

 // Initialize display

 if (!display.begin(I2C_ADDRESS, true)) {

   while (1); // Stop if display fails

 }

 display.clearDisplay();

}

void loop() {

 // read the input on analog pin 0:

 int sensorValue = analogRead(A0);

 sensorValue=map(sensorValue, 40, 1000, 0, 200);  //change range of value

 Serial.println(sensorValue);

 analogWrite(motorPin, sensorValue);

 delay(1000);  // delay in between reads for stability

//-------------------------------------

 float t = dht22.getTemperature();

 float h = dht22.getHumidity();

 if (dht22.getLastError() != dht22.OK) {

   Serial.print("last error :");

   Serial.println(dht22.getLastError());

 }

//------------------------------------------------------

 Serial.print("h=");Serial.print(h,1);Serial.print("\t");

 Serial.print("t=");Serial.println(t,1);

 delay(2000); //Collecting period should be : >1.7 second

 // nothing needed

 // Connect or reconnect to WiFi

 if(WiFi.status() != WL_CONNECTED){

   Serial.print("Attempting to connect to SSID: ");

   Serial.println(SECRET_SSID);

   while(WiFi.status() != WL_CONNECTED){

     WiFi.begin(ssid, pass);  // Connect to WPA/WPA2 network. Change this line if using open or WEP network

     Serial.print(".");

     delay(5000);    

   }

   Serial.println("\nConnected.");

 }

 display.clearDisplay();

   // Set text properties

 display.setTextSize(2);

 display.setTextColor(SH110X_WHITE);

 display.setCursor(0,0);

 display.print("T= ");          // x, y (top-left)

 display.println(t);

 display.print("H= ");

 display.println(h);

 display.print("L= ");

 display.println(sensorValue);

 display.display();                   // push to screen

 // set the fields with the values

 ThingSpeak.setField(1, t);

 ThingSpeak.setField(2, sensorValue);

 ThingSpeak.setField(3, h);

 // set the status

 ThingSpeak.setStatus(myStatus);

  // write to the ThingSpeak channel

 int x = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

 if(x == 200){

   Serial.println("Channel update successful.");

 }

 else{

   Serial.println("Problem updating channel. HTTP error code " + String(x));

 }

  delay(20000); // Wait 20 seconds to update the channel again

}