Connecting ESP8266 to a BMP280 Sensor and LCD

Components Required

• ESP8266 development board (e.g., NodeMCU or Wemos D1 Mini) (Affiliate) – https://s.click.aliexpress.com/e/_DD3JQhj
• BMP280 Pressure and Temperature Sensor (Affiliate) – https://s.click.aliexpress.com/e/_DDVxAVX

• 2004 LCD module (with I2C interface) – (Affiliate) – https://s.click.aliexpress.com/e/_DE4GaZb
• Breadboard and jumper wires (Affiliate) – https://s.click.aliexpress.com/e/_Dl5kuk1

Inicial Wiring (Optional)

BMP280 to ESP8266

• VCC (BMP280) to 3.3V (ESP8266)
• GND (BMP280) to GND (ESP8266)
• SDA (BMP280) to D2 (ESP8266)
• SCL (BMP280) to D1 (ESP8266)

BMP280 I2C Address

To find the I2C address of a BMP280 sensor, you can use an I2C scanner sketch. This sketch will scan the I2C bus for devices and print out their addresses. Here’s a simple I2C scanner sketch:

#include <Wire.h>

void setup() {
  Wire.begin();
  Serial.begin(115200);
  while (!Serial); // Wait for serial monitor to open
  Serial.println("\nI2C Scanner");
}

void loop() {
  byte error, address;
  int nDevices;

  Serial.println("Scanning...");

  nDevices = 0;
  for(address = 1; address < 127; address++ ) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address<16) 
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");

      nDevices++;
    }
    else if (error==4) {
      Serial.print("Unknown error at address 0x");
      if (address<16) 
        Serial.print("0");
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");

  delay(5000); // Wait 5 seconds for next scan
}

Final Wiring

BMP280 to ESP8266

• VCC (BMP280) to 3.3V (ESP8266)
• GND (BMP280) to GND (ESP8266)
• SDA (BMP280) to D2 (ESP8266)
• SCL (BMP280) to D1 (ESP8266)

LCD 2004 to ESP8266 (External regulated power source)

• VCC (LCD) to 5V
• GND (LCD) to GND
• SDA (LCD) to D2 (ESP8266)
• SCL (LCD) to D1 (ESP8266)

Libraries Required

• Adafruit BMP280 Library: This library is used to interface the BMP280 sensor with the ESP8266.

• Adafruit Unified Sensor Library: This library is required by the BMP280 library.

• LiquidCrystal_I2C Library: This library is used to control the LCD display.

Code

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP280.h>
#include <LiquidCrystal_I2C.h>

#define hPA 1;
#define Bar 0.001;
float BAR_Show;
//Pressure in BAR
//BAR_Show=(((bmp.readPressure() / 100.0F)*Bar)/hPA);

#define SEALEVELPRESSURE_HPA (1010)

Adafruit_BMP280 bmp; // I2C
LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C address 0x27, 20 column and 4 rows

void setup() {
  Serial.begin(115200);
  lcd.begin(20, 4);

  lcd.init();

   // Initialize 2004 LCD display
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("BMP280 & 2004 LCD");
  lcd.setCursor(0, 1);
  lcd.print("Temperature:");
  lcd.setCursor(0, 2);
  lcd.print("Pressure:");
  lcd.setCursor(0, 3);
  lcd.print("Altitude:");
 
  if (!bmp.begin(0x76)) {
    Serial.println("Could not find a valid BMP280 sensor, check wiring!");
    while (1);
  }
}

void loop() {
  lcd.setCursor(12, 1);  
  lcd.print(bmp.readTemperature());
  lcd.print(" *C");

  lcd.setCursor(9, 2);  
  lcd.print(bmp.readPressure() / 100.0F);
  lcd.print(" hPA");

  lcd.setCursor(9, 3); 
  lcd.print(bmp.readAltitude(SEALEVELPRESSURE_HPA));
  lcd.print(" m");

  delay(1000);
}

Explanation

• The code begins by including the necessary libraries. The Adafruit BMP280 library is used to interface with the BMP280 sensor, and the LiquidCrystal_I2C library is used to control the LCD display.
• In the setup function, we initialize the serial communication for debugging purposes and the LCD display. We also check if the BMP280 sensor is correctly connected.
• In the loop function, we read the temperature, pressure, and altitude data from the BMP280 sensor and display it on the LCD. The temperature is displayed in Celsius, the pressure in hPa, and the altitude in meters. The data is updated every 1 second.
• In this code, you can adjust the SEALEVELPRESSURE_HPA variable to the current sea level pressure at your location. This will give you a more accurate altitude reading. The bmp.readAltitude(SEALEVELPRESSURE_HPA) function calculates the altitude based on the pressure at sea level.
• In this code, replace “0x76” with the I2C address of your BMP280 sensor.
• The bmp.begin() function initializes the sensor and returns true if the sensor is found and false otherwise.
• The bmp.readTemperature(), bmp.readPressure(), and bmp.readAltitude() functions are used to read the temperature, pressure, and approximate altitude, respectively.

Conclusion

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