BME680_Class Class Reference

Main BME680 class for the temperature / humidity / pressure sensor. More...

#include <Zanshin_BME680.h>

Inherited by BME680.

Public Member Functions
	BME680_Class ()
	~BME680_Class ()
bool	begin ()
bool	begin (const uint32_t i2cSpeed)
bool	begin (const uint8_t chipSelect)
bool	begin (const uint32_t i2cSpeed, const uint8_t i2cAddress)
bool	begin (const uint8_t chipSelect, const uint8_t mosi, const uint8_t miso, const uint8_t sck)
uint8_t	setOversampling (const uint8_t sensor, const uint8_t sampling=UINT8_MAX) const
bool	setGas (uint16_t GasTemp, uint16_t GasMillis) const
uint8_t	setIIRFilter (const uint8_t iirFilterSetting=UINT8_MAX) const
uint8_t	getSensorData (int32_t &temp, int32_t &hum, int32_t &press, int32_t &gas, const bool waitSwitch=true)
uint8_t	getI2CAddress () const
void	reset ()
bool	measuring () const
	true if currently measuring
void	triggerMeasurement () const
	trigger a measurement

Private Member Functions
bool	commonInitialization ()
	Common initialization code.
uint8_t	readByte (const uint8_t addr) const
	Read byte from register address.
uint8_t	readSensors (const bool waitSwitch)
	read the registers in one burst
void	waitForReadings () const
	Wait for readings to finish.
void	getCalibration ()
	Load calibration from registers.
template<typename T >
uint8_t &	getData (const uint8_t addr, T &value) const
template<typename T >
uint8_t &	putData (const uint8_t addr, const T &value) const

Private Attributes
uint8_t	_I2CAddress = 0
	Default is I2C address is unknown.
uint16_t	_I2CSpeed = 0
	Default is I2C speed is unknown.
uint8_t	_cs
uint8_t	_sck
uint8_t	_mosi
uint8_t	_miso
	Hardware and software SPI pins.
uint8_t	_H6
uint8_t	_P10
uint8_t	_res_heat_range
	unsigned configuration vars
int8_t	_H3
int8_t	_H4
int8_t	_H5
int8_t	_H7
int8_t	_G1
int8_t	_G3
int8_t	_T3
int8_t	_P3
int8_t	_P6
int8_t	_P7
int8_t	_res_heat
int8_t	_rng_sw_err
	signed configuration vars
uint16_t	_H1
uint16_t	_H2
uint16_t	_T1
uint16_t	_P1
	unsigned 16bit configuration vars
int16_t	_G2
int16_t	_T2
int16_t	_P2
int16_t	_P4
int16_t	_P5
int16_t	_P8
int16_t	_P9
	signed 16bit configuration vars
int32_t	_tfine
int32_t	_Temperature
int32_t	_Pressure
int32_t	_Humidity
int32_t	_Gas
	signed 32bit configuration vars

Detailed Description

Main BME680 class for the temperature / humidity / pressure sensor.

Constructor & Destructor Documentation

BME680_Class()

BME680_Class::BME680_Class

(

)

Class constructor

Currently empty and unused

~BME680_Class()

BME680_Class::~BME680_Class

(

)

Class destructor

Currently empty and unused

Member Function Documentation

begin() [1/5]

bool BME680_Class::begin

(

)

starts communications with device (overloaded)

When called with no parameters the I2C protocol with I2C_STANDARD_MODE speed is selected. The I2C network is searched for the first BME680 device. return "true" if successful otherwise false

begin() [2/5]

bool BME680_Class::begin

(

const uint32_t

i2cSpeed

)

starts communications with device (overloaded)

When called with a 32-bit parameter it is assumed that the I2C protocol is to be used and the speed setting is determined by the parameter.

Parameters

[in]

i2cSpeed

I2C Speed value return "true" if successful otherwise false

begin() [3/5]

bool BME680_Class::begin	(	const uint32_t	i2cSpeed,
		const uint8_t	i2cAddress )

starts communications with device (overloaded)

When called with a 32-bit parameter it is assumed that the I2C protocol is to be used and the speed setting is determined by the parameter. If the i2cAddress is 0 then check both, otherwise check only only the specified address

Parameters

[in]	i2cSpeed	I2C Speed value
[in]	i2cAddress	I2C Address, use 0 to self-determine return "true" if successful otherwise false

begin() [4/5]

bool BME680_Class::begin

(

const uint8_t

chipSelect

)

starts communications with device (overloaded)

When called with a single 8-bit parameter is assumed that hardware SPI is to be used if the value is not 0x76 or 0x77, in which case it is assumed that it is the I2C addr

Parameters

[in]

chipSelect

Arduino Pin number for the Slave-Select pin or the I2C address return "true" if successful otherwise false

begin() [5/5]

bool BME680_Class::begin	(	const uint8_t	chipSelect,
		const uint8_t	mosi,
		const uint8_t	miso,
		const uint8_t	sck )

starts communications with device (overloaded)

When called with 4 parameters then software SPI is assumed

Parameters

[in]	chipSelect	Arduino Pin number for the Slave-Select pin
[in]	mosi	Arduino Pin number for the Master-out-Slave-in pin
[in]	miso	Arduino Pin number for the Master-in-Slave-out pin
[in]	sck	Arduino Pin number for the System clock pin return "true" if successful otherwise false

commonInitialization()

bool BME680_Class::commonInitialization ( )

private

Common initialization code.

Common BME680 initialization function

Called from all of the overloaded "begin()" functions once the communications protocol has been selected return "true" if successful otherwise false

getCalibration()

void BME680_Class::getCalibration ( )

private

Load calibration from registers.

reads the calibration register data into local variables for use in converting readings

The calibration registers are read into a temporary array and then parsed into the appropriate calibration variables, this was taken from the example BOSCH software and minimizes register reads, but makes it rather difficult to read. This will be redone for legibility at some point in the future param[in] addr Address of device return single byte read

getData()

template<typename T >

uint8_t & BME680_Class::getData ( const uint8_t addr, T & value ) const

inlineprivate

functions

Declare the getData and putData methods as template functions. All device I/O is done through these two functions regardless of whether I2C, hardware SPI or software SPI is being used. The two functions are designed so that only the address and a variable are passed in and the functions determine the size of the parameter variable and reads or writes that many bytes. So if a read is called using a character array[10] then 10 bytes are read, if called with a int8 then only one byte is read. The return value, if used, is the number of bytes read or written. Since this is implemented by using template function definitions, they need to be defined in this header file rather than in the c++ program library file. The "getData()" function is currently not used in the library directly, but the function "readByte()" is used which calls the getData(). The "putData()" is called directly in the code.

Template for reading from I2C or SPI using any data type

As a template it can support compile-time data type definitions

Parameters

[in]	addr	Memory address
[in]	value	Data Type "T" to read

Returns

Size of data read in bytes

getI2CAddress()

uint8_t BME680_Class::getI2CAddress

(

)

const

Returns the I2C address of the BME680 return I2C Address from private variables

getSensorData()

uint8_t BME680_Class::getSensorData	(	int32_t &	temp,
		int32_t &	hum,
		int32_t &	press,
		int32_t &	gas,
		const bool	waitSwitch = true )

Returns the most recent temperature, humidity and pressure readings param[out] temp Temperature reading param[out] hum Humidity reading param[out] press Pressure reading param[out] gas Gas reading param[in] waitSwitch (Optional) When set will not return until reading is finished

measuring()

bool BME680_Class::measuring

(

)

const

true if currently measuring

Returns whether the BME680 is currently measuring return "true" if a measurement is active, otherwise "false"

putData()

template<typename T >

uint8_t & BME680_Class::putData ( const uint8_t addr, const T & value ) const

inlineprivate

Template for writing to I2C or SPI using any data type

As a template it can support compile-time data type definitions

Parameters

[in]	addr	Memory address
[in]	value	Data Type "T" to write

Returns

Size of data written in bytes

readByte()

uint8_t BME680_Class::readByte ( const uint8_t addr ) const

private

Read byte from register address.

Read a single byte from the given address

interlude function to the "getData()" function. This is called so that the return value is the byte of data that has just been read rather than the number of bytes read returned by "getData()" param[in] addr Address of device return single byte of read from addr

readSensors()

uint8_t BME680_Class::readSensors ( const bool waitSwitch )

private

read the registers in one burst

reads all 4 sensor values from the registers in one operation and then proceeds to convert the raw temperature, pressure & humidity readings into standard metric units

The formula is written in the BME680's documentation but the math used below was taken from Adafruit's Adafruit_BME680_Library at https://github.com/adafruit/Adafruit_BME680. I think it can be refactored into more efficient code at some point in the future, but it does work correctly. param[in] waitSwitch (Optional) When set will not return until reading is finished

Lookup table for the possible gas range values

reset()

void BME680_Class::reset

(

)

Performs a device reset

setGas()

bool BME680_Class::setGas	(	uint16_t	GasTemp,
		uint16_t	GasMillis ) const

sets the gas measurement target temperature and heating time param[in] GasTemp Target temperature in Celsius param[in] GasMillis Milliseconds to turn on heater return Always returns "true"

setIIRFilter()

uint8_t BME680_Class::setIIRFilter

(

const uint8_t

iirFilterSetting = UINT8_MAX

)

const

Set or return the current IIR filter setting

When called with no parameters returns the current IIR Filter setting, otherwise when called with one parameter will set the IIR filter value and return the new setting param[in] iirFilterSetting New setting return IIR Filter setting

setOversampling()

uint8_t BME680_Class::setOversampling	(	const uint8_t	sensor,
		const uint8_t	sampling = UINT8_MAX ) const

sets the oversampling mode for the sensor

See enumerated "sensorTypes" for a list of values. Set to a valid oversampling rate as defined in the enumerated type oversamplingTypes. If either value is out of range or another error occurs then the return value is false. param[in] sensor Enumerated sensor type param[in] sampling Sampling rate from enumerated type return "true" if successful otherwise false

triggerMeasurement()

void BME680_Class::triggerMeasurement

(

)

const

trigger a measurement

Trigger a new measurement on the BME680

waitForReadings()

void BME680_Class::waitForReadings ( ) const

private

Wait for readings to finish.

Only returns once a measurement on the BME680 has completed

Member Data Documentation

_cs

uint8_t BME680_Class::_cs

private

_G1

int8_t BME680_Class::_G1

private

_G2

int16_t BME680_Class::_G2

private

_G3

int8_t BME680_Class::_G3

private

_Gas

int32_t BME680_Class::_Gas

private

signed 32bit configuration vars

_H1

uint16_t BME680_Class::_H1

private

_H2

uint16_t BME680_Class::_H2

private

_H3

int8_t BME680_Class::_H3

private

_H4

int8_t BME680_Class::_H4

private

_H5

int8_t BME680_Class::_H5

private

_H6

uint8_t BME680_Class::_H6

private

_H7

int8_t BME680_Class::_H7

private

_Humidity

int32_t BME680_Class::_Humidity

private

_I2CAddress

uint8_t BME680_Class::_I2CAddress = 0

private

Default is I2C address is unknown.

_I2CSpeed

uint16_t BME680_Class::_I2CSpeed = 0

private

Default is I2C speed is unknown.

_miso

uint8_t BME680_Class::_miso

private

Hardware and software SPI pins.

_mosi

uint8_t BME680_Class::_mosi

private

_P1

uint16_t BME680_Class::_P1

private

unsigned 16bit configuration vars

_P10

uint8_t BME680_Class::_P10

private

_P2

int16_t BME680_Class::_P2

private

_P3

int8_t BME680_Class::_P3

private

_P4

int16_t BME680_Class::_P4

private

_P5

int16_t BME680_Class::_P5

private

_P6

int8_t BME680_Class::_P6

private

_P7

int8_t BME680_Class::_P7

private

_P8

int16_t BME680_Class::_P8

private

_P9

int16_t BME680_Class::_P9

private

signed 16bit configuration vars

_Pressure

int32_t BME680_Class::_Pressure

private

_res_heat

int8_t BME680_Class::_res_heat

private

_res_heat_range

uint8_t BME680_Class::_res_heat_range

private

unsigned configuration vars

_rng_sw_err

int8_t BME680_Class::_rng_sw_err

private

signed configuration vars

_sck

uint8_t BME680_Class::_sck

private

_T1

uint16_t BME680_Class::_T1

private

_T2

int16_t BME680_Class::_T2

private

_T3

int8_t BME680_Class::_T3

private

_Temperature

int32_t BME680_Class::_Temperature

private

_tfine

int32_t BME680_Class::_tfine

private

---

The documentation for this class was generated from the following files:

• Zanshin_BME680.h
• Zanshin_BME680.cpp