BME280 Arduino I2C

This is a simple and straightforward library for the BME280 temperature, pressure and humidity sensor.

Library is using I2C interface to communicate with the sensor.

The main purpose of this library is to make an easy-to-follow example of communication with BME280 over I2C.

Current state and limitations

• Configurable BME280 I2C address. Default is 0x76. Some sensors may have 0x77.
• Configurable TwoWires instance if needed.
• Configurable humidity, temperature and pressure oversampling
  • Default: x1
  • For convenience you can use BME280_OVERSAMPLING_X1, BME280_OVERSAMPLING_X2, BME280_OVERSAMPLING_X4, BME280_OVERSAMPLING_X8, BME280_OVERSAMPLING_X16
• Configurable sensor mode
  • Default: Normal
  • Normal, Sleep, Forced modes are supported
• Configurable sensor standby time
  • Default: 1000
  • Per BME280 datasheet, 0.5, 62.5, 125, 250, 500, 1000, 10, 20 msec
• Configurable IIR filter
  • Default: Off
  • Off, 2, 4, 8, 16

Installation

Look for BME280_Arduino_I2C library in Arduino library manager or PlatformIO library manager.

Dependencies

None

Measurements

The library provides a consumer with 3 measurements:

• Temperature: float, 2 decimals, ° C
  • You can convert ° C to ° F use F = 1.8 * C + 32 formula.
• Pressure: float, Pa
  • You can convert to the preferred unit from Pascals. Example: mmHg = Pa * 0.00750062
• Humidity: uint8_t, %

Interface

• Constructor supports 2 optional arguments
  • int bmeAddress, I2C address of a sensor, default is 0x76
  • TwoWire* customTwoWire, a pointer to the TwoWire instance, default to &Wire
• uint8_t begin() - initialization method. Should be called before any readings can be performed, recommended to call in a setup function
  • returns 0 if sensor is found, calibration data is received and configuration is sent to the sensor
  • returns 1 if TwoWire request failed
  • returns 2 if sensor is not found
• bool setHumiditySettings(uint8_t os = BME280_OVERSAMPLING_X1) - set humidity oversampling
  • os can be between 1 and 5 inclusively, where 1 - x1, 2 - x2, 3 - x4, 4 - x8, 5 - x16.
  • returns false if arguments are invalid, true otherwise
• bool setGeneralSettings(uint8_t tOS = BME280_OVERSAMPLING_X1, uint8_t pOS = BME280_OVERSAMPLING_X1, uint8_t m = 3) - sets temperature and pressure oversampling, sensor mode
  • tOS can be between 1 and 5 inclusively, where 1 - x1, 2 - x2, 3 - x4, 4 - x8, 5 - x16.
  • pOS can be between 1 and 5 inclusively, where 1 - x1, 2 - x2, 3 - x4, 4 - x8, 5 - x16.
  • m can be between 0 and 3 inclusively, where 0 - Sleep, 1 and 2 - Forced, 3 - Normal.
  • returns false if arguments are invalid, true otherwise
• bool setConfigs(uint8_t tsb = 5, uint8_t filter = 0) - sets general sensor configuration
  • tsb can be between 0 and 7 inclusively, where 0 - 0.5ms, 1 - 62.5ms, 2 - 125ms, 3 - 250ms, 4 - 500ms, 5 - 1s, 6 - 10ms, 7 - 20ms.
  • filter can be between 0 and 4 inclusively, where 0 - off, 1 - 2, 2 - 4, 3 - 8, 4 - 16.
  • returns false if arguments are invalid, true otherwise
• BME280Data* read() - reads temperature, humidity and pressure and returns a pointer to the data structure
  • returns nullptr if sensor has not been initialized (begin method had not been called) or TwoWire request failed
  • returns BME280Data* with float temperature, float pressure and uint8_t humidity fields if reading is successful. NOTE: if read function is called more frequently than current sensor standby, previous values will be returned

Usage

Make sure you wire your SCL and SCA inputs to the supported GPIOs.

Wiring

TODO

Code

#include <BME280_Arduino_I2C.h>

BME280_Arduino_I2C bme;

void setup() {
    if (bme.begin() == 0) {
        // Initialized
    } else {
        /*
            Failed to initialize:
            Returning code 1: Wire is not available
            Returning code 2: Device has not been found
        */
    }
}

void loop() {
    BME280Data* data = bme.read();

    // nullptr if read failed
     if (data != nullptr) {
        // data->temperature
        // data->humidity
        // data->pressure
    }
}

Support

Tested on Arduino Nano (nanoatmega328), ESP32 (espressif32 esp32dev). Most likely works on any other boards with I2C support.