API for the BMA250E 10 bit Triaxial Accelerometer. More...

Detailed Description

ID: bma250e
Name: Digital Triaxial Acceleration Sensor
Category: accelerometer
Manufacturer: bosch
Connection: i2c spi gpio
Link: https://www.bosch-sensortec.com/bst/products/all_products/bma250e

The BMA250E is a triaxial, low-g acceleration sensor with digital output for consumer applications. It allows measurements of acceleration in three perpendicular axes. An evaluation circuitry (ASIC) converts the output of a micromechanical acceleration-sensing structure (MEMS) that works according to the differential capacitance principle.

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 driver attempts to support verious flavors of this chip, such as the version on the BMX050, BMI050 (chipid 0xfa) and the version on the bmc050 (chipid 0x03). Not all functionality is appropriate, or even present on all chips. Consult the relevant datasheets.

This device requires 3.3v operation.

    // Instantiate an BMA250E using default I2C parameters
    upm::BMA250E sensor;
    // For SPI, bus 0, you would pass -1 as the address, and a valid pin
    // for CS: BMA250E(0, -1, 10);
    // now output data every 250 milliseconds
    while (shouldRun) {
        float x, y, z;
        sensor.update();
        sensor.getAccelerometer(&x, &y, &z);
        cout << "Accelerometer x: " << x << " y: " << y << " z: " << z << " g" << endl;
        // we show both C and F for temperature
        cout << "Compensation Temperature: " << sensor.getTemperature() << " C / "
             << sensor.getTemperature(true) << " F" << endl;
        cout << endl;
        upm_delay_us(250000);
    }

Public Member Functions
	BMA250E (int bus=BMA250E_DEFAULT_I2C_BUS, int addr=BMA250E_DEFAULT_ADDR, int cs=-1)

	~BMA250E ()

void	update ()

uint8_t	getChipID ()

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

std::vector< float >	getAccelerometer ()

float	getTemperature (bool fahrenheit=false)

void	init (BMA250E_POWER_MODE_T pwr=BMA250E_POWER_MODE_NORMAL, BMA250E_RANGE_T range=BMA250E_RANGE_2G, BMA250E_BW_T bw=BMA250E_BW_250)

void	reset ()

void	setRange (BMA250E_RANGE_T range)

void	setBandwidth (BMA250E_BW_T bw)

void	setPowerMode (BMA250E_POWER_MODE_T power)

void	enableFIFO (bool useFIFO)

void	fifoSetWatermark (int wm)

void	fifoConfig (BMA250E_FIFO_MODE_T mode, BMA250E_FIFO_DATA_SEL_T axes)

void	setSelfTest (bool sign, bool amp, BMA250E_SELFTTEST_AXIS_T axis)

uint8_t	getInterruptEnable0 ()

void	setInterruptEnable0 (uint8_t bits)

uint8_t	getInterruptEnable1 ()

void	setInterruptEnable1 (uint8_t bits)

uint8_t	getInterruptEnable2 ()

void	setInterruptEnable2 (uint8_t bits)

uint8_t	getInterruptMap0 ()

void	setInterruptMap0 (uint8_t bits)

uint8_t	getInterruptMap1 ()

void	setInterruptMap1 (uint8_t bits)

uint8_t	getInterruptMap2 ()

void	setInterruptMap2 (uint8_t bits)

uint8_t	getInterruptSrc ()

void	setInterruptSrc (uint8_t bits)

uint8_t	getInterruptOutputControl ()

void	setInterruptOutputControl (uint8_t bits)

void	clearInterruptLatches ()

BMA250E_RST_LATCH_T	getInterruptLatchBehavior ()

void	setInterruptLatchBehavior (BMA250E_RST_LATCH_T latch)

uint8_t	getInterruptStatus0 ()

uint8_t	getInterruptStatus1 ()

uint8_t	getInterruptStatus2 ()

uint8_t	getInterruptStatus3Bits ()

BMA250E_ORIENT_T	getInterruptStatus3Orientation ()

void	enableRegisterShadowing (bool shadow)

void	enableOutputFiltering (bool filter)

void	setLowPowerMode2 ()

void	installISR (BMA250E_INTERRUPT_PINS_T intr, int gpio, mraa::Edge level, void(isr)(void ), void *arg)

void	uninstallISR (BMA250E_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
bma250e_context	m_bma250e

Constructor & Destructor Documentation

BMA250E	(	int	bus = `BMA250E_DEFAULT_I2C_BUS`,
		int	addr = `BMA250E_DEFAULT_ADDR`,
		int	cs = `-1`
	)

BMA250E 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 initialization failure.

~BMA250E ( )

BMA250E 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 getAccelerometer	(	float *	x,
		float *	y,
		float *	z
	)

Return accelerometer data in gravities. 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 > getAccelerometer ( )

Return accelerometer data in gravities 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.

float getTemperature ( bool fahrenheit = false )

Return the current measured temperature. Note, this is not ambient temperature. 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.

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void init	(	BMA250E_POWER_MODE_T	pwr = `BMA250E_POWER_MODE_NORMAL`,
		BMA250E_RANGE_T	range = `BMA250E_RANGE_2G`,
		BMA250E_BW_T	bw = `BMA250E_BW_250`
	)

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.

Parameters

pwr	One of the BMA250E_POWER_MODE_T values. The default is BMA250E_POWER_MODE_NORMAL.
range	One of the BMA250E_RANGE_T values. The default is BMA250E_RANGE_2G.
bw	One of the filtering BMA250E_BW_T values. The default is BMA250E_BW_250.

Exceptions

std::runtime_error on failure.

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void reset ( )

Reset the device as if during a power on reset. All configured values are lost when this happens. You should call init() afterwards, or at least perform the same initialization init() does before continuing.

Exceptions

std::runtime_error on failure.

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void setRange ( BMA250E_RANGE_T range )

Set the acceleration scaling range. This device supports 2, 4, 8, and 16g ranges.

Parameters

range One of the BMA250E_RANGE_T values.

Exceptions

std::runtime_error on failure.

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void setBandwidth ( BMA250E_BW_T bw )

Set the output filtering bandwidth of the device.

Parameters

bw	One of the BMA250E_BW_T values.

Exceptions

std::runtime_error on failure.

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void setPowerMode ( BMA250E_POWER_MODE_T power )

Set the power mode of the device. Care must be taken when setting a low power or suspend mode. By default init() calls setLowPowerMode2() to ensure that if any of these modes are entered we can still talk to the device. The default low power mode is LPM1, which requires slowing down register writes, which we cannot support. setLowPowerMode2() enables LPM2 which keeps the digital interface operational in low power or suspend modes. See the datasheet for details.

So if you reset your device and don't call init() or setLowPowerMode2(), you could lose control of the device by calling this function with anything other than POWER_MODE_NORMAL. You've been warned :)

Parameters

power One of the BMA250E_POWER_MODE_T values.

Exceptions

std::runtime_error on failure.

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void enableFIFO ( bool useFIFO )

Enable update() to read from the FIFO rather than the acceleration axis registers directly. init() enables this mode by default if the chip variant supports a FIFO. An advantage to this mode that all axis data is sampled from the same timeslice. When reading directly from the acceleration output registers, it's possible for one axis to be updated while another is being read, causing a temporal anomaly that even Captain Picard can't resolve. If there is no FIFO present, this call is ignored.

Using the FIFO removes this problem.

Parameters

useFIFO True to enable update() to read from the FIFO. When false, update will read from the acceleration output registers directly.

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void fifoSetWatermark ( int wm )

Set the FIFO watermark. When the watermark is reached an interrupt (if enabled) will be generated. If there is no FIFO present, this call is ignored.

Parameters

wm	The FIFO watermark to use. The maximum value is 63.

Exceptions

std::runtime_error on failure.

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void fifoConfig	(	BMA250E_FIFO_MODE_T	mode,
		BMA250E_FIFO_DATA_SEL_T	axes
	)

Set the FIFO configuration. init() uses the FIFO_MODE_BYPASS mode with axes set to FIFO_DATA_SEL_XYZ by default. If there is no FIFO present, this call is ignored.

Parameters

mode	One of the BMA250E_FIFO_MODE_T values.
axes	One of the BMA250E_FIFO_DATA_SEL_T values.

Exceptions

std::runtime_error on failure.

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void setSelfTest	(	bool	sign,
		bool	amp,
		BMA250E_SELFTTEST_AXIS_T	axis
	)

Enable, disable, and configure the built in self test on a per axis basis. See the datasheet for details.

Parameters

sign	True for a positive deflection, false for negative
amp	True for a high deflection, false for a low deflection
axis	One of the BMA250E_SELFTTEST_AXIS_T values. Note, only one axis at a time can be tested. Accelerometer output for other axes should be ignored.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptEnable0 ( )

Return the Interrupt Enables 0 register. These registers allow you to enable various interrupt conditions. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_EN_0_BITS_T bits.

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void setInterruptEnable0 ( uint8_t bits )

Set the Interrupt Enables 0 register. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_EN_0_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptEnable1 ( )

Return the Interrupt Enables 1 register. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_EN_1_BITS_T bits.

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void setInterruptEnable1 ( uint8_t bits )

Set the Interrupt Enables 1 register. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_EN_1_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptEnable2 ( )

Return the Interrupt Enables 2 register. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_EN_2_BITS_T bits.

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void setInterruptEnable2 ( uint8_t bits )

Set the Interrupt Enables 2 register. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_EN_2_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptMap0 ( )

Return the Interrupt Map 0 register. These registers allow you to map specific interrupts to the interrupt 1 or interrupt 2 pin. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_MAP_0_BITS_T bits.

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void setInterruptMap0 ( uint8_t bits )

Set the Interrupt Map 0 register. These registers allow you to map specific interrupts to the interrupt 1 or interrupt 2 pin. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_MAP_0_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptMap1 ( )

Return the Interrupt Map 1 register. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_MAP_1_BITS_T bits.

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void setInterruptMap1 ( uint8_t bits )

Set the Interrupt Map 1 register. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_MAP_1_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptMap2 ( )

Return the Interrupt Map 2 register. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_MAP_2_BITS_T bits.

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void setInterruptMap2 ( uint8_t bits )

Set the Interrupt Map 2 register. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_MAP_2_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptSrc ( )

Return the Interrupt source register. This register allows determining where data comes from (filtered/unfiltered) for those interrupt sources where this is selectable. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_SRC_BITS_T bits.

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void setInterruptSrc ( uint8_t bits )

Set the Interrupt source register. This register allows determining where data comes from (filtered/unfiltered) for those interrupt sources where this is selectable. See the datasheet for details.

Parameters

bits	A bitmask of BMA250E_INT_SRC_BITS_T bits.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptOutputControl ( )

Return the Interrupt output control 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.

Returns: A bitmask of BMA250E_INT_OUT_CTRL_BITS_T bits.

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void setInterruptOutputControl ( uint8_t bits )

Set the Interrupt output control 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 BMA250E_INT_OUT_CTRL_BITS_T bits.

Exceptions

std::runtime_error on failure.

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void clearInterruptLatches ( )

Clear all latched interrupts. See the datasheet for details.

Exceptions

std::runtime_error on failure.

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BMA250E_RST_LATCH_T getInterruptLatchBehavior ( )

Return the current interrupt latching behavior. See the datasheet for details.

Returns: One of the BMA250E_RST_LATCH_T values.

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void setInterruptLatchBehavior ( BMA250E_RST_LATCH_T latch )

Set the current interrupt latching behavior. See the datasheet for details.

Parameters

latch One of the BMA250E_RST_LATCH_T values.

Exceptions

std::runtime_error on failure.

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uint8_t getInterruptStatus0 ( )

Return the interrupt status 0 register. These registers indicate which interrupts have been triggered. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_STATUS_0_BITS_T bits.

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uint8_t getInterruptStatus1 ( )

Return the interrupt status 1 register. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_STATUS_1_BITS_T bits.

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uint8_t getInterruptStatus2 ( )

Return the interrupt status 2 register. See the datasheet for details.

Returns: A bitmask of BMA250E_INT_STATUS_2_BITS_T bits.

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uint8_t getInterruptStatus3Bits ( )

Return the interrupt status 3 register bitfields. See the datasheet for details. The Orientation value is not returned by this function, see getInterruptStatus3Orientation() for that information.

Returns: A bitmask of BMA250E_INT_STATUS_3_BITS_T bits ONLY.

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BMA250E_ORIENT_T getInterruptStatus3Orientation ( )

Return the interrupt status 3 register Orientation value. See the datasheet for details.

Returns: One of the BMA250E_ORIENT_T values.

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void enableRegisterShadowing ( bool shadow )

Enable shadowing of the accelerometer output registers. When enabled, a read of an axis LSB register automatically locks the MSB register of that axis until it has been read. This is usually a good thing to have enabled. init() enables this by default. If disabled, then it becomes possible for part of an axis value to change while another part is being read, causing inconsistent data.

Parameters

shadow True to enable axis register shadowing, false otherwise.

Exceptions

std::runtime_error on failure.

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void enableOutputFiltering ( bool filter )

Enable filtering of the accelerometer axis data. init() enables this by default. If disabled, then accelerometer data that is read will be raw and unfiltered (rated R). See the datasheet for details.

Parameters

filter True to enable filtering, false to disable.

Exceptions

std::runtime_error on failure.

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void setLowPowerMode2 ( )

Make sure low power mode config (LPM2) is set in case we later go into the low power or suspend power modes. LPM1 mode (the default) requires drastically slowed register writes which we cannot handle.

Exceptions

std::runtime_error on failure.

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void installISR	(	BMA250E_INTERRUPT_PINS_T	intr,
		int	gpio,
		mraa::Edge	level,
		void()(void )	isr,
		void *	arg
	)

install an interrupt handler.

Parameters

intr	One of the BMA250E_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.