API for the BMP280 Digital Pressure Sensor. More...

Detailed Description

ID: bmp280
Name: BMP280 Digital Pressure Sensor
Category: pressure
Manufacturer: adafruit
Connection: i2c spi gpio
Link: https://www.adafruit.com/products/2651

The BMP280 is an absolute barometric pressure sensor especially designed for mobile applications. The sensor module is housed in an extremely compact 8-pin metal-lid LGA package with a footprint of only 2.0 × 2.5 mm2 and 0.95 mm package height. Its small dimensions and its low power consumption of 2.7 μA @1Hz allow the implementation in battery driven devices such as mobile phones, GPS modules or watches.

As the successor to the widely adopted BMP180, the BMP280 delivers high performance in all applications that require precise pressure measurement. The BMP280 operates at lower noise, supports new filter modes and an SPI interface within a footprint 63% smaller than the BMP180.

  // Instantiate a BMP280 instance using default i2c bus and address
  upm::BMP280 *sensor = new upm::BMP280();
  // For SPI, bus 0, you would pass -1 as the address, and a valid pin for CS:
  // BMP280(0, -1, 10);
  while (shouldRun)
    {
      // update our values from the sensor
      sensor->update();
      // we show both C and F for temperature
      cout << "Compensation Temperature: " << sensor->getTemperature()
           << " C / " << sensor->getTemperature(true) << " F"
           << endl;
      cout << "Pressure: " << sensor->getPressure() << " Pa" << endl;
      cout << "Computed Altitude: " << sensor->getAltitude() << " m" << endl;
      cout << endl;
      sleep(1);
    }

Public Types
enum	BMP280_REGS_T : uint8_t { REG_CALIB00 = 0x88, REG_CALIB01 = 0x89, REG_CALIB02 = 0x8a, REG_CALIB03 = 0x8b, REG_CALIB04 = 0x8c, REG_CALIB05 = 0x8d, REG_CALIB06 = 0x8e, REG_CALIB07 = 0x8f, REG_CALIB08 = 0x90, REG_CALIB09 = 0x91, REG_CALIB10 = 0x92, REG_CALIB11 = 0x93, REG_CALIB12 = 0x94, REG_CALIB13 = 0x95, REG_CALIB14 = 0x96, REG_CALIB15 = 0x97, REG_CALIB16 = 0x98, REG_CALIB17 = 0x99, REG_CALIB18 = 0x9a, REG_CALIB19 = 0x9b, REG_CALIB20 = 0x9c, REG_CALIB21 = 0x9d, REG_CALIB22 = 0x9e, REG_CALIB23 = 0x9f, REG_CALIB24 = 0xa0, REG_CALIB25 = 0xa1, REG_CHIPID = 0xd0, REG_RESET = 0xe0, REG_STATUS = 0xf3, REG_CTRL_MEAS = 0xf4, REG_CONFIG = 0xf5, REG_PRESSURE_MSB = 0xf7, REG_PRESSURE_LSB = 0xf8, REG_PRESSURE_XLSB = 0xf9, REG_TEMPERATURE_MSB = 0xfa, REG_TEMPERATURE_LSB = 0xfb, REG_TEMPERATURE_XLSB = 0xfc }

enum	CONFIG_BITS_T { CONFIG_SPI3W_EN = 0x01, CONFIG_FILTER0 = 0x04, CONFIG_FILTER1 = 0x08, CONFIG_FILTER2 = 0x10, _CONFIG_FILTER_MASK = 7, _CONFIG_FILTER_SHIFT = 2, CONFIG_T_SB0 = 0x20, CONFIG_T_SB1 = 0x40, CONFIG_T_SB2 = 0x80, _CONFIG_T_SB_MASK = 7, _CONFIG_T_SB_SHIFT = 5 }

enum	FILTER_T { FILTER_OFF = 0, FILTER_2 = 1, FILTER_4 = 2, FILTER_8 = 3, FILTER_16 = 4 }

enum	T_SB_T { T_SB_0_5 = 0, T_SB_62_5 = 1, T_SB_125 = 2, T_SB_250 = 3, T_SB_500 = 4, T_SB_1000 = 5, T_SB_2000 = 6, T_SB_4000 = 7 }

enum	CTRL_MEAS_T { CTRL_MEAS_MODE0 = 0x01, CTRL_MEAS_MODE1 = 0x02, _CTRL_MEAS_MODE_MASK = 3, _CTRL_MEAS_MODE_SHIFT = 0, CTRL_MEAS_OSRS_P0 = 0x04, CTRL_MEAS_OSRS_P1 = 0x08, CTRL_MEAS_OSRS_P2 = 0x10, _CTRL_MEAS_OSRS_P_MASK = 7, _CTRL_MEAS_OSRS_P_SHIFT = 2, CTRL_MEAS_OSRS_T0 = 0x04, CTRL_MEAS_OSRS_T1 = 0x08, CTRL_MEAS_OSRS_T2 = 0x10, _CTRL_MEAS_OSRS_T_MASK = 7, _CTRL_MEAS_OSRS_T_SHIFT = 5 }

enum	MODES_T { MODE_SLEEP = 0, MODE_FORCED = 1, MODE_NORMAL = 3 }

enum	OSRS_P_T { OSRS_P_SKIPPED = 0, OSRS_P_OVERSAMPLING_1 = 1, OSRS_P_OVERSAMPLING_2 = 2, OSRS_P_OVERSAMPLING_4 = 3, OSRS_P_OVERSAMPLING_8 = 4, OSRS_P_OVERSAMPLING_16 = 5 }

enum	OSRS_T_T { OSRS_T_SKIPPED = 0, OSRS_T_OVERSAMPLING_1 = 1, OSRS_T_OVERSAMPLING_2 = 2, OSRS_T_OVERSAMPLING_4 = 3, OSRS_T_OVERSAMPLING_8 = 4, OSRS_T_OVERSAMPLING_16 = 5 }

enum	STATUS_T { STATUS_IM_UPDATE = 0x01, STATUS_MEASURING = 0x08 }

enum	USAGE_MODE_T { USAGE_MODE_HANDHELD_LOW_POWER = 0, USAGE_MODE_HANDHELD_DYNAMIC = 1, USAGE_MODE_WEATHER_MONITOR = 2, USAGE_MODE_FLOOR_CHG_DETECT = 3, USAGE_MODE_DROP_DETECT = 4, USAGE_MODE_INDOOR_NAV = 5 }

Public Member Functions
	BMP280 (int bus=BMP280_DEFAULT_I2C_BUS, int addr=BMP280_DEFAULT_ADDR, int cs=-1, uint8_t theChipID=BMP280_DEFAULT_CHIPID)

virtual	~BMP280 ()

virtual void	update ()

uint8_t	getChipID ()

void	reset ()

float	getTemperature (bool fahrenheit=false)

float	getPressure ()

float	getAltitude (float seaLevelhPA=1013.25)

virtual void	setUsageMode (USAGE_MODE_T mode)

void	setOversampleRateTemperature (OSRS_T_T rate)

void	setOversampleRatePressure (OSRS_P_T rate)

void	setTimerStandby (T_SB_T tsb)

void	setFilter (FILTER_T filter)

void	setMeasureMode (MODES_T mode)

const char *	getModuleName ()

int	getTemperatureCelsius ()

int	getPressurePa ()

Data Fields
const uint8_t	BMP280_RESET_BYTE = 0xb6

const int	CALIBRATION_BYTES = 26

Protected Member Functions
uint8_t	getStatus ()

uint8_t	readReg (uint8_t reg)

int	readRegs (uint8_t reg, uint8_t *buffer, int len)

void	writeReg (uint8_t reg, uint8_t val)

void	clearData ()

virtual void	readCalibrationData ()

void	csOn ()

void	csOff ()

Protected Attributes
mraa::I2c *	m_i2c

mraa::Spi *	m_spi

mraa::Gpio *	m_gpioCS

uint8_t	m_addr

float	m_temperature

float	m_pressure

int32_t	m_t_fine

MODES_T	m_mode

Member Enumeration Documentation

enum BMP280_REGS_T : uint8_t

BMP280 registers

enum CONFIG_BITS_T

REG_CONFIG bits

enum FILTER_T

FILTER values (samples to reach >= 75% of step response)

enum T_SB_T

T_SB values (timer standby)

enum CTRL_MEAS_T

REG_CTRL_MEAS bits

enum MODES_T

CTRL_MEAS_MODE values

enum OSRS_P_T

CTRL_MEAS_OSRS_P values

enum OSRS_T_T

CTRL_MEAS_OSRS_T values

enum STATUS_T

REG_STATUS bits

enum USAGE_MODE_T

USAGE_MODE values. This is a fake specification to configure the various knobs based on their typical use modes, as recommended by Bosch.

Constructor & Destructor Documentation

BMP280	(	int	bus = `BMP280_DEFAULT_I2C_BUS`,
		int	addr = `BMP280_DEFAULT_ADDR`,
		int	cs = `-1`,
		uint8_t	theChipID = `BMP280_DEFAULT_CHIPID`
	)

BMP280 constructor.

This device can support both I2C and SPI. For SPI, set the addr to -1, and specify a positive integer representing the Chip Select (CS) pin for the cs argument. If you are using a hardware CS pin, then you can connect the proper pin to the hardware CS pin on your MCU and supply -1 for cs. The default operating mode is I2C.

Parameters

bus	I2C or SPI bus to use.
address	The address for this device. -1 for SPI.
cs	The gpio pin to use for the SPI Chip Select. -1 for I2C or for SPI with a hardware controlled pin.
theChipID	The chip ID to use for validation

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~BMP280 ( )

virtual

BMP280 Destructor.

Member Function Documentation

void update ( void )

virtual

Update the internal stored values from sensor data.

Reimplemented in BME280.

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uint8_t getChipID ( )

Return the chip ID.

Returns: The chip ID (BMP280_CHIPID).

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void reset ( )

Reset the sensor, as if by a power-on-reset.

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float getTemperature ( bool fahrenheit = false )

Return the current measured temperature. Note, this is not ambient temperature - this is the temperature used to fine tune the pressure measurement. update() must have been called prior to calling this method.

Parameters

fahrenheit true to return data in Fahrenheit, false for Celicus. Celsius is the default.

Returns: The temperature in degrees Celsius or Fahrenheit.

float getPressure ( )

Return the current measured pressure in Pascals (Pa). update() must have been called prior to calling this method.

Returns: The pressure in Pascals (Pa).

float getAltitude ( float seaLevelhPA = 1013.25 )

Return the current computed altitude in meters. update() must have been called prior to calling this method.

Parameters

seaLevelhPA The pressure at sea level in hectoPascals (hPa). The default is 1013.25 hPA, (101325 Pa).

Returns: The computed altitude in meters.

void setUsageMode ( USAGE_MODE_T mode )

virtual

Set a general usage mode. This function can be used to configure the filters and oversampling for a particular use case. These setting are documented in the BMP280 datasheet. The default mode set in the contructor is USAGE_MODE_INDOOR_NAV, the highest resolution mode.

Parameters

mode	One of the USAGE_MODE_T values.

Reimplemented in BME280.

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void setOversampleRateTemperature ( OSRS_T_T rate )

Set the temperature sensor oversampling parameter. See the data sheet for details. This value can be automatically set to a suitable value by using one of the predefined modes for setUsageMode().

Parameters

mode	One of the OSRS_T_T values.

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void setOversampleRatePressure ( OSRS_P_T rate )

Set the pressure sensor oversampling parameter. See the data sheet for details. This value can be automatically set to a suitable value by using one of the predefined modes for setUsageMode().

Parameters

mode	One of the OSRS_P_T values.

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void setTimerStandby ( T_SB_T tsb )

Set the timer standby value. When in NORMAL operating mode, this timer governs how long the chip will wait before performing a measurement. See the data sheet for details.

Parameters

mode	One of the T_SB_T values.

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void setFilter ( FILTER_T filter )

Set the IIR filtering parameter. See the data sheet for details. This value can be automatically set to a suitable value by using one of the predefined modes for setUsageMode().

Parameters

mode	One of the FILTER_T values.

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void setMeasureMode ( MODES_T mode )

Set the default measuring mode. Basic values are forced, sleep, and normal. See the data sheet for details. This value can be automatically set to a suitable value by using one of the predefined modes for setUsageMode().

Parameters