Pressure & Altitude
Interfacing BMP280 Pressure & Altitude with ESP32
What is the BMP280?
The BMP280 is a low-power digital sensor that reads barometric pressure and temperature over I2C or SPI. Pressure readings can be converted to altitude, making it popular for weather stations and altitude-tracking drones. As the successor to the BMP180, it offers lower power consumption, faster measurement conversion, and the flexibility of either I2C or SPI wiring, while remaining one of the cheapest and most widely supported pressure sensors in the hobbyist ecosystem.
Specifications
| Sensor type | Bosch BMP280 barometric pressure and temperature sensor |
| Operating voltage | 1.71V–3.6V DC (breakout boards regulate from 3.3-5V input) |
| Operating current | ~2.7 µA at 1 sample/second in standard operating mode |
| Pressure range | 300 hPa to 1100 hPa |
| Pressure resolution | 0.16 Pa (relative resolution equivalent to roughly ~1cm of altitude change) |
| Temperature accuracy | ±1°C typical |
| Interface | I2C (up to 3.4MHz) or SPI (up to 10MHz), selectable via wiring/solder jumper on most breakout boards |
| I2C address | 0x76 or 0x77, depending on the SDO pin state |
BMP280 Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VIN / VCC | Power, 3.3–5V DC depending on breakout regulator |
| 2 | GND | Ground |
| 3 | SCL / SCK | I2C clock or SPI clock, depending on interface mode |
| 4 | SDA / SDI | I2C data or SPI data-in, depending on interface mode |
| 5 | CSB | Chip select — ties HIGH for I2C mode on most breakouts, or used as SPI chip select when in SPI mode |
| 6 | SDO | Sets the I2C address (0x76 when LOW, 0x77 when HIGH); doubles as SPI data-out in SPI mode |
Most breakout boards default to I2C mode with CSB tied HIGH; the SDO pin's state determines which of the two possible I2C addresses (0x76 or 0x77) the sensor uses, which is handy when running two BMP280-family sensors on the same bus. As with any pressure-based altitude sensor, calibrate against a known local sea-level pressure reading for meaningful absolute altitude results.
Setting Up BMP280 with ESP32
Library
Adafruit BMP280 Library by Adafruit
Arduino IDE → Tools → Manage Libraries → search "Adafruit BMP280"
Wiring
| Component pin | ESP32 pin | Note |
|---|---|---|
| VIN / VCC | 3.3V | — |
| GND | GND | — |
| SCL / SCK | GPIO22 | — |
| SDA / SDI | GPIO21 | — |
| CSB | 3.3V | Tie HIGH to select I2C mode |
| SDO | GND or 3.3V | Sets I2C address: LOW = 0x76, HIGH = 0x77 -- match this to the address used in code |
Example code
ESP32 default I2C pins are 21 (SDA) / 22 (SCL) but any GPIO pair works with Wire.begin(sda, scl). Match bmp.begin()'s address argument to how SDO is wired.
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