Sensor driver for the Bosch BME680 air quality sensor. This library supports i2c and 4-wire SPI connections, reads temperature, pressure, relative humidity, and VOC levels, and provides limited support for adjusting the sensors settings. More...

#include "simpletools.h"

Data Structures
struct	bme680_st

Macros
#define	BME680_H

#define	CELSIUS (0)

#define	FAHRENHEIT (1)

#define	KELVIN (2)

#define	PASCALS (0)

#define	MMHG (1)

#define	INHG (2)

#define	PSI (3)

#define	METERS (0)

#define	FEET (1)

#define	BME680_OS_NONE (0)

#define	BME680_OS_1X (1)

#define	BME680_OS_2X (2)

#define	BME680_OS_4X (3)

#define	BME680_OS_8X (4)

#define	BME680_OS_16X (5)

#define	BME680_FILTER_SIZE_0 (0)

#define	BME680_FILTER_SIZE_1 (1)

#define	BME680_FILTER_SIZE_3 (2)

#define	BME680_FILTER_SIZE_7 (3)

#define	BME680_FILTER_SIZE_15 (4)

#define	BME680_FILTER_SIZE_31 (5)

#define	BME680_FILTER_SIZE_63 (6)

#define	BME680_FILTER_SIZE_127 (7)

#define	BME680_SETTING_AMB_TEMP (0)

#define	BME680_SETTING_HEATER_TEMP (1)

#define	BME680_SETTING_HEATER_DURATION (2)

#define	BME680_SETTING_FILTER_SIZE (3)

#define	BME680_SETTING_TEMP_SAMPLES (4)

#define	BME680_SETTING_PRESSURE_SAMPLES (5)

#define	BME680_SETTING_HUMIDITY_SAMPLES (6)

Typedefs
typedef struct bme680_st	bme680_t

typedef bme680_t	bme680

Functions
bme680_t *	bme680_openI2C (i2c *i2c_bus, char i2c_addr)
	Initialize a BME680 sensor into i2c mode. More...

bme680_t *	bme680_openSPI (char pin_sdo, char pin_clk, char pin_sdi, char pin_cs)
	Initialize a BME680 sensor into 4-wire SPI mode. More...

void	bme680_begin (bme680_t *dev)
	Internal function used to set the values in the bme680_t structure to their default values. More...

char	bme680_loadSettings (bme680_t *dev)
	Loads settings values that have been saved in the bme680_t structure into the BME680 sensor. More...

char	bme680_readSensor (bme680_t *dev)
	Instructs the BME680 sensor to take a reading. Readings take approximately 200ms and should be retireved using bme680_temperature(), bme680_pressure(), bme680_humidity(), bme680_altitude(), and bme680_gasResistance(). More...

void	bme680_write (bme680_t dev, unsigned char reg_addr, unsigned char reg_data, unsigned short len)
	Internal function used to read values from the specified registers of the BME680 sensor. More...

void	bme680_read (bme680_t dev, unsigned char reg_addr, unsigned char reg_data, unsigned short len)
	Internal function used to write values to the specified registers of the BME680 sensor. More...

void	bme680_configure (bme680_t *dev, char setting, int value)
	Change configurable settings for the BME680 sensor. More...

void	bme680_close (bme680_t *dev)
	Close and free the memory used by the bme680 device structure. More...

float	bme680_temperature (bme680_t *dev, char unit)
	Retrieve the temperature from the last read of the BME680 device. More...

float	bme680_pressure (bme680_t *dev, char unit)
	Retrieve the temperature from the last read of the BME680 device. More...

float	bme680_altitude (bme680_t *dev, char unit)
	Retrieve the estimated altitude from the last read of the BME680 device. More...

float	bme680_humidity (bme680_t *dev)
	Retrieve the relative humidity as a percentage from the last read of the BME680 device. More...

float	bme680_gasResistance (bme680_t *dev)
	Retrieve the relative humidity as a percentage from the last read of the BME680 device. More...

void	bme680_heaterEnable (bme680_t *dev)
	Allows the BME680 to send current to the heating element for its gas sensor. More...

void	bme680_heaterDisable (bme680_t *dev)
	Turns off the current that the BME680 sends to the heating element for its gas sensor. More...

Detailed Description

Sensor driver for the Bosch BME680 air quality sensor. This library supports i2c and 4-wire SPI connections, reads temperature, pressure, relative humidity, and VOC levels, and provides limited support for adjusting the sensors settings.

Author: Matthew Matz

Version: 0.5

Copyright: Copyright (C) Parallax, Inc. 2019. All Rights MIT Licensed.

Macro Definition Documentation

◆ BME680_FILTER_SIZE_0

#define BME680_FILTER_SIZE_0 (0)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_1

#define BME680_FILTER_SIZE_1 (1)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_127

#define BME680_FILTER_SIZE_127 (7)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_15

#define BME680_FILTER_SIZE_15 (4)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_3

#define BME680_FILTER_SIZE_3 (2)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_31

#define BME680_FILTER_SIZE_31 (5)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_63

#define BME680_FILTER_SIZE_63 (6)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_FILTER_SIZE_7

#define BME680_FILTER_SIZE_7 (3)

IIR (Low-pass) filter setting used in bme680_configure()

◆ BME680_OS_16X

#define BME680_OS_16X (5)

Over-sampling setting (16x) used in bme680_configure()

◆ BME680_OS_1X

#define BME680_OS_1X (1)

Over-sampling setting (1x) used in bme680_configure()

◆ BME680_OS_2X

#define BME680_OS_2X (2)

Over-sampling setting (2x) used in bme680_configure()

◆ BME680_OS_4X

#define BME680_OS_4X (3)

Over-sampling setting (4x) used in bme680_configure()

◆ BME680_OS_8X

#define BME680_OS_8X (4)

Over-sampling setting (8x) used in bme680_configure()

◆ BME680_OS_NONE

#define BME680_OS_NONE (0)

Over-sampling setting (None) used in bme680_configure()

◆ BME680_SETTING_AMB_TEMP

#define BME680_SETTING_AMB_TEMP (0)

Setting constant used in bme680_configure()

◆ BME680_SETTING_FILTER_SIZE

#define BME680_SETTING_FILTER_SIZE (3)

Setting constant used in bme680_configure()

◆ BME680_SETTING_HEATER_DURATION

#define BME680_SETTING_HEATER_DURATION (2)

Setting constant used in bme680_configure()

◆ BME680_SETTING_HEATER_TEMP

#define BME680_SETTING_HEATER_TEMP (1)

Setting constant used in bme680_configure()

◆ BME680_SETTING_HUMIDITY_SAMPLES

#define BME680_SETTING_HUMIDITY_SAMPLES (6)

Setting constant used in bme680_configure()

◆ BME680_SETTING_PRESSURE_SAMPLES

#define BME680_SETTING_PRESSURE_SAMPLES (5)

Setting constant used in bme680_configure()

◆ BME680_SETTING_TEMP_SAMPLES

#define BME680_SETTING_TEMP_SAMPLES (4)

Setting constant used in bme680_configure()

◆ CELSIUS

#define CELSIUS (0)

Measurement Unit for bme680_temperature()

◆ FAHRENHEIT

#define FAHRENHEIT (1)

Measurement Unit for bme680_temperature()

◆ FEET

#define FEET (1)

Measurement Unit for bme680_altitude()

◆ INHG

#define INHG (2)

Measurement Unit for bme680_pressure()

◆ KELVIN

#define KELVIN (2)

Measurement Unit for bme680_temperature()

◆ METERS

#define METERS (0)

Measurement Unit for bme680_altitude()

◆ MMHG

#define MMHG (1)

Measurement Unit for bme680_pressure()

◆ PASCALS

#define PASCALS (0)

Measurement Unit for bme680_pressure()

◆ PSI

#define PSI (3)

Measurement Unit for bme680_pressure()

Function Documentation

◆ bme680_altitude()

float bme680_altitude	(	bme680_t *	dev,
		char	unit
	)

Retrieve the estimated altitude from the last read of the BME680 device.

Note: this is calcualted from the pressure measurement. It is not reliable for high altitudes, and it is affected by the ambient (barometric) pressure due to weather. For that reason, the BME680 is better for measuring changes in altitude versus absolute altitude.

Parameters

*dev	Pointer to the bme680 device.
unit	Unit of meaure to return the measurement in. May be METERS or FEET.

◆ bme680_begin()

void bme680_begin ( bme680_t * dev )

Internal function used to set the values in the bme680_t structure to their default values.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_close()

void bme680_close ( bme680_t * dev )

Close and free the memory used by the bme680 device structure.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_configure()

void bme680_configure	(	bme680_t *	dev,
		char	setting,
		int	value
	)

Change configurable settings for the BME680 sensor.

Parameters

*dev	pointer to the bme680 device.
setting	the setting to change. May be

Ambient Temperature in deg C (BME680_SETTING_AMB_TEMP) - default is 25. Heater Temperature in deg C (BME680_SETTING_HEATER_TEMP) - default is 320. Heater Duration in ms (BME680_SETTING_HEATER_DURATION) - default is 150. Low-pass filter size (BME680_SETTING_FILTER_SIZE) - default is BME680_FILTER_SIZE_3. Temperature samples to take (BME680_SETTING_TEMP_SAMPLES) - default is BME680_OS_8X. Pressure samples to take (BME680_SETTING_PRESSURE_SAMPLES) - default is BME680_OS_4X. Humidity samples to take (BME680_SETTING_HUMIDITY_SAMPLES) - default is BME680_OS_2X.

Parameters

value the value to write into that setting.

◆ bme680_gasResistance()

float bme680_gasResistance ( bme680_t * dev )

Retrieve the relative humidity as a percentage from the last read of the BME680 device.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_heaterDisable()

void bme680_heaterDisable ( bme680_t * dev )

Turns off the current that the BME680 sends to the heating element for its gas sensor.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_heaterEnable()

void bme680_heaterEnable ( bme680_t * dev )

Allows the BME680 to send current to the heating element for its gas sensor.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_humidity()

float bme680_humidity ( bme680_t * dev )

Retrieve the relative humidity as a percentage from the last read of the BME680 device.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_loadSettings()

char bme680_loadSettings ( bme680_t * dev )

Loads settings values that have been saved in the bme680_t structure into the BME680 sensor.

Note: Must be called after calling bem680_init...() and before calling bme_readSensor().

Parameters

*dev	pointer to the bme680 device.

◆ bme680_openI2C()

bme680_t* bme680_openI2C	(	i2c *	i2c_bus,
		char	i2c_addr
	)

Initialize a BME680 sensor into i2c mode.

Parameters

*i2c_bus	pointer to an i2c bus that has already been opened with i2c_open();.
i2c_addr	the i2c address of the device, usualy 0x76 or 0x77.

Returns: bme680_t device identifier for use with functions in bme680 library.

◆ bme680_openSPI()

bme680_t* bme680_openSPI	(	char	pin_sdo,
		char	pin_clk,
		char	pin_sdi,
		char	pin_cs
	)

Initialize a BME680 sensor into 4-wire SPI mode.

Parameters

pin_sdo	the BME680's SDO (MISO) pin.
pin_clk	the BME680's CLK (clock) pin.
pin_sdi	the BME680's SDI (MOSI) pin.
pin_cs	the BME680's CS (select) pin.

Returns: bme680_t device identifier for use with functions in bme680 library.

◆ bme680_pressure()

float bme680_pressure	(	bme680_t *	dev,
		char	unit
	)

Retrieve the temperature from the last read of the BME680 device.

Parameters

*dev	pointer to the bme680 device.
unit	Unit of meaure to return the measurement in. May be PASCALS, MMHG, INHG, or PSI.

◆ bme680_read()

void bme680_read	(	bme680_t *	dev,
		unsigned char	reg_addr,
		unsigned char *	reg_data,
		unsigned short	len
	)

Internal function used to write values to the specified registers of the BME680 sensor.

Parameters

*dev	pointer to the bme680 device.
reg_addr	the address of first register to write to.
*reg_data	the array containing alternating data and address bytes to write.
len	the total number of data and address bytes to write.

◆ bme680_readSensor()

char bme680_readSensor ( bme680_t * dev )

Instructs the BME680 sensor to take a reading.
Readings take approximately 200ms and should be retireved using bme680_temperature(), bme680_pressure(), bme680_humidity(), bme680_altitude(), and bme680_gasResistance().

Note: The internal heating element for the gas (VOC) sensor can skew temperature and humidity readings if the sensor is read at intervals of under 3 seconds. If frequent temperature and humidity readings are desired, use bme680_heaterDisable() to prevent the heating element from turning on.

Parameters

*dev	pointer to the bme680 device.

◆ bme680_temperature()

float bme680_temperature	(	bme680_t *	dev,
		char	unit
	)

Retrieve the temperature from the last read of the BME680 device.

Parameters

*dev	Pointer to the bme680 device.
unit	Unit of meaure to return the measurement in. May be CELSIUS, FAHRENHEIT, or KELVIN

◆ bme680_write()

void bme680_write	(	bme680_t *	dev,
		unsigned char	reg_addr,
		unsigned char *	reg_data,
		unsigned short	len
	)

Internal function used to read values from the specified registers of the BME680 sensor.

Parameters

*dev	pointer to the bme680 device.
reg_addr	the address of register to begin reading from.
*reg_data	the array to store the received data into.
len	the number of bytes to read.

Data Structures

Macros

Typedefs

Functions

Detailed Description

Macro Definition Documentation

◆ BME680_FILTER_SIZE_0

◆ BME680_FILTER_SIZE_1

◆ BME680_FILTER_SIZE_127

◆ BME680_FILTER_SIZE_15

◆ BME680_FILTER_SIZE_3

◆ BME680_FILTER_SIZE_31

◆ BME680_FILTER_SIZE_63

◆ BME680_FILTER_SIZE_7

◆ BME680_OS_16X

◆ BME680_OS_1X

◆ BME680_OS_2X

◆ BME680_OS_4X

◆ BME680_OS_8X

◆ BME680_OS_NONE

◆ BME680_SETTING_AMB_TEMP

◆ BME680_SETTING_FILTER_SIZE

◆ BME680_SETTING_HEATER_DURATION

◆ BME680_SETTING_HEATER_TEMP

◆ BME680_SETTING_HUMIDITY_SAMPLES

◆ BME680_SETTING_PRESSURE_SAMPLES

◆ BME680_SETTING_TEMP_SAMPLES

◆ CELSIUS

◆ FAHRENHEIT

◆ FEET

◆ INHG

◆ KELVIN

◆ METERS

◆ MMHG

◆ PASCALS

◆ PSI

Function Documentation

◆ bme680_altitude()

◆ bme680_begin()

◆ bme680_close()

◆ bme680_configure()

◆ bme680_gasResistance()

◆ bme680_heaterDisable()

◆ bme680_heaterEnable()

◆ bme680_humidity()

◆ bme680_loadSettings()

◆ bme680_openI2C()

◆ bme680_openSPI()

◆ bme680_pressure()

◆ bme680_read()

◆ bme680_readSensor()

◆ bme680_temperature()

◆ bme680_write()