BME280

BME280 digital pressure, temperature and humidity sensor

Description

Platform independent driver for the Bosch BME280 combined pressure, temperature and humidity sensor.

The core (bme280.c / bme280.h) is written in plain C and knows nothing about the underlying hardware. Everything hardware related is provided by a thin platform layer living in platform/<platform>.

• Interface: I2C or SPI, selected with dev.intf (BME280_INTF_I2C / BME280_INTF_SPI)
• Default I2C address: BME280_DEFAULT_I2C_ADDRESS (0x77)
• Oversampling (bme280_sensor_sampling), IIR filter (bme280_sensor_filter), standby time (bme280_standby_duration) and power mode (bme280_sensor_mode: sleep / forced / normal) are configurable
• Derived readings: altitude via bme280_read_altitude() and sea level pressure via bme280_sea_level_for_altitude(), referenced to SEA_LEVEL_PRESSURE_HPA

Supported platforms

Platform	Files
Arduino	platform/arduino/bme280-arduino.{h,cpp}
Mbed	platform/mbed/bme280-mbed.{h,cpp}
STM32 Cube HAL	platform/stm32cube/bme280-cube-hal.{h,c}

Usage

Demo code showing how to use the library on the ARDUINO platform:

#include "BME280/platform/arduino/bme280-arduino.h"

#define BME280_SDA_PIN 21
#define BME280_SCL_PIN 22

bme280 dev;
bme280_arduino arduino_dev;

void setup()
{
    Serial.begin(115200);

    arduino_dev.i2c.hndl = &Wire;
    arduino_dev.i2c.sda_pin = BME280_SDA_PIN;
    arduino_dev.i2c.scl_pin = BME280_SCL_PIN;

    dev.intf = BME280_INTF_I2C;
    dev.i2c_addr = BME280_DEFAULT_I2C_ADDRESS;
    dev.t_fine = 0;
    dev.t_fine_adjust = 0;
    dev.burst_read_mode = false;

    if (!bme280_arduino_init(&dev, &arduino_dev))
    {
        Serial.println("BME280 init failed!");
    }
}

void loop()
{
    float temperature = 0.0f;
    float pressure = 0.0f;
    float humidity = 0.0f;
    float altitude = 0.0f;

    if (bme280_read_data(&dev, &temperature, &pressure, &humidity))
    {
        Serial.print("T: "); Serial.print(temperature); Serial.print(" [C], ");
        Serial.print("P: "); Serial.print(pressure / 100.0f); Serial.print(" [hPa], ");
        Serial.print("H: "); Serial.print(humidity); Serial.println(" [%]");
    }

    if (bme280_read_altitude(&dev, SEA_LEVEL_PRESSURE_HPA, &altitude))
    {
        Serial.print("Altitude: "); Serial.print(altitude); Serial.println(" [m]");
    }

    delay(1000);
}

Porting to a different platform

To port this library to another platform you only have to implement the HW dependent functions declared at the bottom of bme280.h:

• bme280_write()
• bme280_read()
• bme280_delay_ms()

and provide a bme280_<platform>_init() helper that stores your platform descriptor in dev->platform_dev. See platform/arduino/bme280-arduino.cpp for a reference implementation.

License

MIT - see the repository root for details.

Author

Lukasz Uszko - lukasz.uszko@gmail.com

• Lukasz Uszko aka luk6xff [lukasz.uszko@gmail.com]