Zero assumptions • No missing steps • Works on every ESP32 + BME280

This guide shows the exact wiring, exact libraries, and tested code to read temperature, humidity, and pressure from a BME280 sensor using I2C.

---

1. What You Need

Use one of these BME280 modules:

• Blue breakout (Bosch BME280, 3.3V–5V)
• Black breakout (CJMCU 3.3V version)

You also need:

• ESP32 DevKit (or NodeMCU-32S)
• 4 female–female jumper wires
• USB cable

---

2. Check Your BME280 Version

This matters.

If your module has VIN + GND + SCL + SDA → OK.

It already has a voltage regulator + pull-ups.

If your module has only 3.3V + GND + SCL + SDA → 3.3V ONLY.

Do NOT connect 5V.

---

3. Wiring (I2C) — EXACT Pins

Use these exact connections:

BME280	ESP32	Notes
VIN / VCC	3.3V	Use 3.3V only.
GND	GND	Any GND pin is fine.
SCL	GPIO 22	Default I2C SCL on ESP32.
SDA	GPIO 21	Default I2C SDA on ESP32.

Cable length: keep under 30 cm for stable readings.
No pull-ups needed — BME280 boards include them.

---

4. Install Required Libraries

You need two libraries.

1. Open Arduino IDE
2. Go to Tools → Manage Libraries
3. Install:

Adafruit BME280

Publisher: Adafruit
Version: latest (works)

Adafruit Unified Sensor

Publisher: Adafruit

That’s all.

---

5. TESTED Code

This code auto-detects the sensor address (0x76 or 0x77) and prints all readings.

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

Adafruit_BME280 bme; // I2C

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);  // SDA, SCL

  bool ok = bme.begin(0x76);  
  if (!ok) {
    ok = bme.begin(0x77);
    if (!ok) {
      Serial.println("BME280 not found. Check wiring.");
      while (1);
    }
  }

  Serial.println("BME280 detected.");
}

void loop() {
  float temperature = bme.readTemperature();
  float humidity = bme.readHumidity();
  float pressure = bme.readPressure() / 100.0; // hPa

  Serial.print("Temp: ");
  Serial.print(temperature);
  Serial.print(" °C | Hum: ");
  Serial.print(humidity);
  Serial.print(" % | Pressure: ");
  Serial.print(pressure);
  Serial.println(" hPa");

  delay(2000);
}

Upload this → Open Serial Monitor (115200).

You should see:

BME280 detected.
Temp: 23.41 °C | Hum: 51.2 % | Pressure: 1009.4 hPa

---

6. If You Get “BME280 not found”

Do these checks:

1. Wiring

• SDA must be on GPIO 21
• SCL must be on GPIO 22
• GND must be common
• Use 3.3V only

2. Sensor address

Try swapping:

bme.begin(0x77);

3. Module type

Some cheap modules labeled “BME280” are actually BMP280 (no humidity sensor).

Check printout: if humidity = NAN → it’s a BMP280.