SparkFun BME280 Breakout Hookup Guide

Contributors: MTaylor

Functions of the Arduino Library

Let's get started by looking at the functions that set up the BME280 Atmospheric Sensor:

Class

In the global scope, construct your sensor object (such as mySensor or pressureSensorA) without arguments.

BME280 mySensor;

Object Parameters and setup()

Rather that passing a bunch of data to the constructor, configuration is accomplished by setting the values of the BME280 type in the setup() function. They are exposed by being public: so use the myName.aVariable = someValue; syntax.

Settable variables of the class BME280:

language:c
//Main Interface and mode settings
uint8_t commInterface;
uint8_t I2CAddress;
uint8_t chipSelectPin;

uint8_t runMode;
uint8_t tStandby;
uint8_t filter;
uint8_t tempOverSample;
uint8_t pressOverSample;
uint8_t humidOverSample;

Functions

.begin();
Initialize the operation of the BME280 module with the following steps:

• Starts up the wiring library for I²C by default
• Checks/Validates BME280 chip ID
• Reads compensation data
• Sets default settings from table
• Sets operational mode to Normal Mode

.beginSPI(uint8_t csPin);
Begins communication with the BME280 over an SPI connection.

.beginI2C(TwoWire &wirePort); or .beginI2C(SoftwareWire &wirePort);
Begins communication with the BME280 over an I²C connection. If #ifdef SoftwareWire_h is defined, then a software I²C connection is used.

.setMode(uint8_t mode);
Sets the operational mode of the sensor. (For more details, see section 3.3 of the datasheet.)

.getMode();
Returns the operational mode of the sensor.

.setStandbyTime(uint8_t timeSetting);
Sets the standby time of the cycle time. (For more details, see section 3.3 and Table 27 of the datasheet.)

.setFilter(uint8_t filterSetting)
Sets the time constant of the IIR filter, which slows down the response time of the sensor inputs based on the number of samples required. (For more details, see section 3.4.4, Table 6, and Figure 7 of the datasheet.)

.setTempOverSample(uint8_t overSampleAmount);
Sets the oversampling option (osrs_t) for the temperature measurements. (Directly influences the noise and resolution of the data.)

.setPressureOverSample(uint8_t overSampleAmount);
Sets the oversampling option (osrs_p) for the pressure measurements. (Directly influences the noise and resolution of the data.)

.setHumidityOverSample(uint8_t overSampleAmount);
Sets the oversampling option (osrs_h) for the humidity measurements. (Directly influences the noise of the data.)

.setI2CAddress(uint8_t address);
Changes the I²C address stored in the library to access the sensor.

.isMeasuring();
Checks the measuring bit of the status register for if the device is taking measurement.

.reset();
Soft resets the sensor. (If called, the begin function must be called before using the sensor again.)

.readFloatPressure();
Reads raw pressure data stored in register and applies output compensation (For more details on the data compensation, see section 4.2 of the datasheet.)

.readFloatHumidity();
Reads raw humidity data stored in register and applies output compensation (For more details on the data compensation, see section 4.2 of the datasheet.)

.readTempC();
Reads raw temperature data stored in register and applies output compensation (For more details on the data compensation, see section 4.2 of the datasheet.)

.readTempF();
Reads raw temperature data stored in register and applies output compensation (For more details on the data compensation, see section 4.2 of the datasheet.)