API for the BMM150 3-Axis Geomagnetic Sensor. More...

Detailed Description

ID: bmm150
Name: 3-axis Geomagnetic Sensor
Other Names: bmm050
Category: compass
Manufacturer: bosch
Connection: i2c spi gpio
Link: https://www.bosch-sensortec.com/bst/products/all_products/bmm150

The BMM150 is a standalone geomagnetic sensor for consumer market applications. It allows measurements of the magnetic field in three perpendicular axes. Based on Bosch's proprietary FlipCore technology, performance and features of BMM150 are carefully tuned and perfectly match the demanding requirements of all 3-axis mobile applications such as electronic compass, navigation or augmented reality.

An evaluation circuitry (ASIC) converts the output of the geomagnetic sensor to digital results which can be read out over the industry standard digital interfaces (SPI and I2C).

Not all functionality of this chip has been implemented in this driver, however all the pieces are present to add any desired functionality. This driver supports both I2C (default) and SPI operation.

This device requires 3.3v operation.

    // Instantiate an BMM150 using default I2C parameters
    upm::BMM150 sensor;
    // For SPI, bus 0, you would pass -1 as the address, and a valid pin
    // for CS: BMM150(0, -1, 10);
    // now output data every 250 milliseconds
    while (shouldRun) {
        float x, y, z;
        sensor.update();
        sensor.getMagnetometer(&x, &y, &z);
        cout << "Magnetometer x: " << x << " y: " << y << " z: " << z << " uT" << endl;
        cout << endl;
        upm_delay_us(250000);
    }

Public Member Functions
	BMM150 (int bus=BMM150_DEFAULT_I2C_BUS, int addr=BMM150_DEFAULT_ADDR, int cs=-1)

	~BMM150 ()

void	update ()

uint8_t	getChipID ()

void	getMagnetometer (float x, float y, float *z)

std::vector< float >	getMagnetometer ()

void	init (BMM150_USAGE_PRESETS_T usage=BMM150_USAGE_HIGH_ACCURACY)

void	setPresetMode (BMM150_USAGE_PRESETS_T usage)

void	reset ()

void	setOutputDataRate (BMM150_DATA_RATE_T odr)

void	setPowerBit (bool power)

void	setOpmode (BMM150_OPERATION_MODE_T opmode)

BMM150_OPERATION_MODE_T	getOpmode ()

uint8_t	getInterruptEnable ()

void	setInterruptEnable (uint8_t bits)

uint8_t	getInterruptConfig ()

void	setInterruptConfig (uint8_t bits)

uint8_t	getInterruptStatus ()

void	setRepetitionsXY (uint8_t reps)

void	setRepetitionsZ (uint8_t reps)

void	installISR (BMM150_INTERRUPT_PINS_T intr, int gpio, mraa::Edge level, void(isr)(void ), void *arg)

void	uninstallISR (BMM150_INTERRUPT_PINS_T intr)

uint8_t	readReg (uint8_t reg)

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

void	writeReg (uint8_t reg, uint8_t val)

Protected Attributes
bmm150_context	m_bmm150

Constructor & Destructor Documentation

BMM150	(	int	bus = `BMM150_DEFAULT_I2C_BUS`,
		int	addr = `BMM150_DEFAULT_ADDR`,
		int	cs = `-1`
	)

BMM150 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 (like edison with arduino breakout), 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.
addr	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.

Exceptions

std::runtime_error on failure.

~BMM150 ( )

BMM150 Destructor.

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Member Function Documentation

void update ( void )

Update the internal stored values from sensor data.

Exceptions

std::runtime_error on failure.

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uint8_t getChipID ( )

Return the chip ID.

Returns: The chip ID.

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void getMagnetometer	(	float *	x,
		float *	y,
		float *	z
	)

Return magnetometer data in micro-Teslas (uT). update() must have been called prior to calling this method.

Parameters

x	Pointer to a floating point value that will have the current x component placed into it.
y	Pointer to a floating point value that will have the current y component placed into it.
z	Pointer to a floating point value that will have the current z component placed into it.

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std::vector< float > getMagnetometer ( )

Return magnetometer data in micro-Teslas (uT) in the form of a floating point vector. update() must have been called prior to calling this method.

Returns: A floating point vector containing x, y, and z in that order.

void init ( BMM150_USAGE_PRESETS_T usage = BMM150_USAGE_HIGH_ACCURACY )

Initialize the device and start operation. This function is called from the constructor so will not typically need to be called by a user unless the device is reset. This method will call setPresetMode() with the passed parameter.

Parameters

usage One of the BMM150_USAGE_PRESETS_T values. The default is BMM150_USAGE_HIGH_ACCURACY.

Exceptions

std::runtime_error on failure.

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void setPresetMode ( BMM150_USAGE_PRESETS_T usage )

Set one of the Bosch recommended preset modes. These modes configure the sensor for varying use cases.

Parameters

usage One of the BMM150_USAGE_PRESETS_T values. The default is BMM150_USAGE_HIGH_ACCURACY.

Exceptions

std::runtime_error on failure.

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void reset ( )

Perform a device soft-reset. The device will be placed in SUSPEND mode afterward with all configured setting lost, so some re-initialization will be required to get data from the sensor. Calling init() will get everything running again.

Exceptions

std::runtime_error on failure.

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void setOutputDataRate ( BMM150_DATA_RATE_T odr )

Set the magnetometer Output Data Rate. See the datasheet for details.

Parameters

odr	One of the BMM150_DATA_RATE_T values.

Exceptions

std::runtime_error on failure.

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void setPowerBit ( bool power )

Set or clear the Power bit. When the power bit is cleared, the device enters a deep suspend mode where only the REG_POWER_CTRL register can be accessed. This bit needs to be enabled for the device to operate. See the datasheet for details. The constructor enables this by default. After a deep suspend mode has been entered, all configured data is lost and the device must be reconfigured (as via init()).

Parameters

power true to enable the bit, false otherwise.

Exceptions

std::runtime_error on failure.

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void setOpmode ( BMM150_OPERATION_MODE_T opmode )

Set the operating mode of the device. See the datasheet for details.

Parameters

opmode One of the BMM150_OPERATION_MODE_T values.

Exceptions

std::runtime_error on failure.

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BMM150_OPERATION_MODE_T getOpmode ( )

Get the current operating mode of the device. See the datasheet for details. The power bit must be one for this method to succeed.

Returns: One of the BMM150_OPERATION_MODE_T values.

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uint8_t getInterruptEnable ( )

Return the Interrupt Enables register. This register allows you to enable various interrupt conditions. See the datasheet for details.

Returns: A bitmask of BMM150_INT_EN_BITS_T bits.

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void setInterruptEnable ( uint8_t bits )

Set the Interrupt Enables register. See the datasheet for details.

Parameters

bits	A bitmask of BMM150_INT_EN_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptConfig ( )

Return the Interrupt Config register. This register allows determining the electrical characteristics of the 2 interrupt pins (open-drain/push-pull and level/edge triggering) as well as other options. See the datasheet for details.

Returns: A bitmask of BMM150_INT_CONFIG_BITS_T bits.

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void setInterruptConfig ( uint8_t bits )

Set the Interrupt Config register. This register allows determining the electrical characteristics of the 2 interrupt pins (open-drain/push-pull and level/edge triggering). See the datasheet for details.

Parameters

bits	A bitmask of BMM150_INT_CONFIG_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptStatus ( )

Return the interrupt status register. This register indicates which interrupts have been triggered. See the datasheet for details.

Returns: a bitmask of BMM150_INT_STATUS_BITS_T bits.

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void setRepetitionsXY ( uint8_t reps )

Set the repetition counter for the X and Y axes. This allows the device to average a number of measurements for a more stable output. See the datasheet for details.

Parameters

reps	A coefficient for specifying the number of repititions to perform. (1 + 2(reps))

Exceptions

std::runtime_error on failure.

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void setRepetitionsZ ( uint8_t reps )

Set the repetition counter for the Z axis. This allows the device to average a number of measurements for a more stable output. See the datasheet for details.

Parameters

reps	A coefficient for specifying the number of repititions to perform. (1 + (reps))

Exceptions

std::runtime_error on failure.

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void installISR	(	BMM150_INTERRUPT_PINS_T	intr,
		int	gpio,
		mraa::Edge	level,
		void()(void )	isr,
		void *	arg
	)

Install an interrupt handler.

Parameters

intr	One of the BMM150_INTERRUPT_PINS_T values specifying which interrupt pin you are installing.
gpio	GPIO pin to use as interrupt pin.
level	The interrupt trigger level (one of mraa::Edge values). Make sure that you have configured the interrupt pin properly for whatever level you choose.
isr	The interrupt handler, accepting a void * argument.
arg	The argument to pass the the interrupt handler.