4. esp8266 displays DHT11 temperature and humidity parameters in real time through OLED

Hardware environment

1、ESP8266 Development board

2、OLED display

This screen is displayed by I2C Control by , A resolution of 128*65, The driver chip is SSD1306 0.96 Inch .

Pins are defined as follows ：

Pin number	Definition	describe
1	GND	Access the development board GND
2	VDD	Access the development board VCC(3.3V–5V)
3	SCK(SCL)	Access the development board I2C Of SCL
4	SDA	Access the development board I2C Of SDA

3、DHT11 Temperature and humidity sensor

DHT11 It is a temperature and humidity sensor , Can pass 2 Foot's Singal(out) Transmit the detected ambient temperature to in real time ESP8266.

Pins are defined as follows ：

Pin number	Definition	describe
1	VCC	Access the development board VCC(3.3V)
2	Singal(out)	Access the development board D5(GPIO14)
3	NC	It's empty
4	GND	Access the development board GND

4、 Wiring way

fritzing Sketch Map ：


Connection physical drawing ：

Software environment

1、 Online installation DHT sensor library for ESPx

Click on Tools --> Management of the library Search for DHT11, Choose to install DHT sensor library for ESPx.

2、 Experiment source code

/************************************************************************************** ESP8266 NodeMCU interfacing with SSD1306 OLED and DHT11 sensor This is a free software with NO WARRANTY. http://simple-circuit.com/ ***************************************************************************************/


#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h> // Include DHT library code

#define OLED_RESET 5 // define SSD1306 OLED reset at ESP8266 GPIO5 (NodeMCU D1)
Adafruit_SSD1306 display(OLED_RESET);

#define DHTPIN 14 // DHT11 data pin is connected to ESP8266 GPIO14 (NodeMCU D5)
#define DHTTYPE DHT11 // DHT11 sensor is used
DHT dht(DHTPIN, DHTTYPE);             // Configure DHT library

char temperature[] = "00.0 C";
char humidity[]    = "00.0 %";

void setup(void)
{
    

 Serial.begin(9600);
 delay(1000);

 Wire.begin(4, 0);           // set I2C pins [SDA = GPIO4 (D2), SCL = GPIO0 (D3)], default clock is 100kHz

 // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
 display.begin(SSD1306_SWITCHCAPVCC, 0x3D);  // initialize with the I2C addr 0x3D (for the 128x64)
 // init done

 dht.begin();                // Initialize the DHT library

 // Clear the display buffer.
 display.clearDisplay();

 display.drawFastHLine(0, 32, SSD1306_LCDWIDTH, WHITE);

 display.setTextSize(1);
 display.setTextColor(WHITE, BLACK);
 display.setCursor(10, 5);
 display.print("DHT11 TEMPERATURE:");
 display.setCursor(19, 37);
 display.print("DHT11 HUMIDITY:");
 display.display();
}

void loop()
{
    
 // Read humidity
 byte RH = dht.readHumidity();
 //Read temperature in degree Celsius
 byte Temp = dht.readTemperature();

 temperature[0] = Temp / 10 + '0';
 temperature[1] = Temp % 10 + '0';
 humidity[0]    = RH / 10   + '0';
 humidity[1]    = RH % 10   + '0';

 // print data on serial monitor
 Serial.printf("Temperature = %02u°C\r\n", Temp);
 Serial.printf("Humidity = %02u %%\r\n\r\n", RH);

 // print data on the SSD1306 display
 display.setCursor(46, 20);
 display.print(temperature);
 display.setCursor(46, 52);
 display.print(humidity);
 display.drawRect(71, 20, 3, 3, WHITE);     // Put degree symbol ( ° )
 display.display();

 delay(1000);

}

Temperature and humidity display experiment

Effect display video

ESP8266 Development version passed OLED real-time display DHT11 Temperature and humidity parameters