Temperature and Humidity Sensor DHT11 with arduino Tutorial – Make OLED Termometer
DHT11 is cheapest temperature and humidity sensor compare to another sensor. It has 3 pins that we can easily interface with arduino. It uses single-bus operation.
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PCB size | 22.0mm X 20.5mm X 1.6mm |
Working voltage | 3.3 or 5V DC |
Operating voltage | 3.3 or 5V DC |
Measurement range | 20-95%RH;0-50℃ |
Resolution | 8bit(temperature),8bit(humidity) |
Compatible interfaces | 2.54 3-pin interface and 4-pin Grove interface(1) |
DHT11 Wiring Diagram with arduino
Connect your DHT11 Sensor with arduino as follow
DHT11 arduino library and Code
Before start to code, you can download library first here.
Copy and paste following code to your arduino.
(adsbygoogle = window.adsbygoogle || []).push({});// Example testing sketch for various DHT humidity/temperature sensors // Written by ladyada, public domain #include "DHT.h" #define DHTPIN 2 // what digital pin we're connected to // Uncomment whatever type you're using! #define DHTTYPE DHT11 // DHT 11 //#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321 //#define DHTTYPE DHT21 // DHT 21 (AM2301) // Connect pin 1 (on the left) of the sensor to +5V // NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1 // to 3.3V instead of 5V! // Connect pin 2 of the sensor to whatever your DHTPIN is // Connect pin 4 (on the right) of the sensor to GROUND // Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor // Initialize DHT sensor. // Note that older versions of this library took an optional third parameter to // tweak the timings for faster processors. This parameter is no longer needed // as the current DHT reading algorithm adjusts itself to work on faster procs. DHT dht(DHTPIN, DHTTYPE); void setup() { Serial.begin(9600); Serial.println("DHTxx test!"); dht.begin(); } void loop() { // Wait a few seconds between measurements. delay(2000); // Reading temperature or humidity takes about 250 milliseconds! // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor) float h = dht.readHumidity(); // Read temperature as Celsius (the default) float t = dht.readTemperature(); // Read temperature as Fahrenheit (isFahrenheit = true) float f = dht.readTemperature(true); // Check if any reads failed and exit early (to try again). if (isnan(h) || isnan(t) || isnan(f)) { Serial.println("Failed to read from DHT sensor!"); return; } // Compute heat index in Fahrenheit (the default) float hif = dht.computeHeatIndex(f, h); // Compute heat index in Celsius (isFahreheit = false) float hic = dht.computeHeatIndex(t, h, false); Serial.print("Humidity: "); Serial.print(h); Serial.print(" %\t"); Serial.print("Temperature: "); Serial.print(t); Serial.print(" *C "); Serial.print(f); Serial.print(" *F\t"); Serial.print("Heat index: "); Serial.print(hic); Serial.print(" *C "); Serial.print(hif); Serial.println(" *F"); }
Upload the code, open serial monitor and now you should see the temperature and humidity read by this sensor.
We have sucessfully read the data from DHT11 sensor. Now let’s try to display the result to OLED display to make it more interesting.
DHT with Arduino and OLED Display
Connect arduino to DHT11 sensor and OLED display like picture below
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Copy and paste following code to your arduino IDE
#include <SPI.h> #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #include <Fonts/FreeMonoBold18pt7b.h> #include "DHT.h" #define DHTPIN 2 #define DHTTYPE DHT11 // DHT 11 DHT dht(DHTPIN, DHTTYPE); int h; int t; #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels // Declaration for an SSD1306 display connected to I2C (SDA, SCL pins) #define OLED_RESET 4 // Reset pin # (or -1 if sharing Arduino reset pin) Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); #define bitmap_height 128 #define bitmap_width 64 static const unsigned char PROGMEM logo_bmp[] = { 0x00, 0x00, 0x00, 0x00, 0xFF, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3F, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1F, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x8F, 0xC0, 0x00, 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0x3C)) { // Address 0x3D for 128x64 Serial.println(F("SSD1306 allocation failed")); for (;;); // Don't proceed, loop forever } // Clear the buffer display.clearDisplay(); printText(); delay(1500); } void loop() { h = dht.readHumidity(); t = dht.readTemperature(); if (isnan(h) || isnan(t)) { Serial.println("Failed to read from DHT sensor!"); return; } showBitmap(); printText(); display.display(); delay(500); display.clearDisplay(); } void printText() { display.setFont(&FreeMonoBold18pt7b); display.setTextColor(WHITE); // Draw white text display.setCursor(45, 28); // Start at top-left corner display.print(t); display.drawCircle(92, 8, 3, WHITE); display.setCursor(100, 27); display.print("C"); display.setCursor(45, 62); display.print(h); display.print("%"); } void showBitmap(void) { display.drawBitmap(0, 0, logo_bmp, bitmap_height, bitmap_width, WHITE); //display.display(); }
Upload the code to arduino, If everything work you should now see OLED display the temperature and humidity of DHT11
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