The BME280 — Three Sensors in One Package
The Bosch BME280 combines a temperature sensor (±1 °C), a humidity sensor (±3% RH), and a barometric pressure sensor (±1 hPa) in a 2.5 mm × 2.5 mm package. It communicates over I2C with just two wires and draws less than 3 µA in sleep mode.
Paired with a 0.96" SSD1306 OLED on the same I2C bus, you get a self-contained weather station that uses only two GPIO pins (A4 and A5 on Uno). We'll display all three readings on screen, calculate altitude from pressure, and draw an up/down arrow when pressure changes more than 2 hPa over 10 minutes.
💡 Tip
Most BME280 breakout boards support both 3.3V and 5V via an onboard regulator. Check your module's datasheet — some have the I2C address jumper set to 0x76; others to 0x77. The default in the Adafruit library is 0x77.
Components
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Wiring (shared I2C bus)
Both the BME280 and OLED share the same SDA/SCL lines:
| Module | VCC | GND | SDA | SCL |
|---|---|---|---|---|
| BME280 | 3.3V | GND | A4 | A5 |
| OLED SSD1306 | 3.3V | GND | A4 | A5 |
No additional resistors needed — both modules include pull-ups.
