API for the LIS3DH 3-axis Accelerometer. More...

Detailed Description

ID: lis3dh
Name: Digital 3-axis Accelerometer
Category: accelerometer
Manufacturer: stmicro
Connection: i2c spi gpio
Link: http://www.st.com/en/mems-and-sensors/lis3dh.html

The LIS3DH is an ultra-low-power high performance three-axis linear accelerometer belonging to the "nano" family which leverages on the robust and mature manufacturing processes already used for the production of micromachined accelerometers.

The LIS3DH has user-selectable full scales of 2g/4g/8g/16g and is capable of measuring accelerations with output data rates from 1 Hz to 5300 Hz.

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.

    // Instantiate an LIS3DH using default I2C parameters
    upm::LIS3DH sensor;
    // For SPI, bus 0, you would pass -1 as the address, and a valid pin
    // for CS: LIS3DH(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
	LIS3DH (int bus=LIS3DH_DEFAULT_I2C_BUS, int addr=LIS3DH_DEFAULT_I2C_ADDR, int cs=-1)

virtual	~LIS3DH ()

void	init (LIS3DH_ODR_T odr=LIS3DH_ODR_100HZ, LIS3DH_FS_T fs=LIS3DH_FS_2G, bool high_res=true)

void	enableAxes (bool x_axis_enable, bool y_axis_enable, bool z_axis_enable)

void	enableBDUMode (bool bdu_enable)

void	enableLPMode (bool lp_enable)

void	enableHRMode (bool hr_enable)

void	enableNormalMode ()

void	enableHPFiltering (bool filter)

void	enableInterruptLatching (bool int1_latch, bool int2_latch)

void	enableADC (bool adc_enable)

void	enableTemperature (bool temperature_enable)

void	setODR (LIS3DH_ODR_T odr)

void	setFullScale (LIS3DH_FS_T fs)

void	setInterruptActiveHigh (bool high)

void	setInt1Config (uint8_t cfg)

void	setInt2Config (uint8_t cfg)

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	update ()

uint8_t	getChipID ()

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

std::vector< float >	getAccelerometer ()

float	getTemperature (bool fahrenheit=false)

uint8_t	getStatus ()

uint8_t	getStatusAux ()

void	installISR (LIS3DH_INTERRUPT_PINS_T intr, int gpio, mraa::Edge level, void(isr)(void ), void *arg)

void	uninstallISR (LIS3DH_INTERRUPT_PINS_T intr)

Protected Attributes
lis3dh_context	m_lis3dh

Constructor & Destructor Documentation

LIS3DH	(	int	bus = `LIS3DH_DEFAULT_I2C_BUS`,
		int	addr = `LIS3DH_DEFAULT_I2C_ADDR`,
		int	cs = `-1`
	)

LIS3DH 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

~LIS3DH ( )

virtual

LIS3DH destructor

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Member Function Documentation

void init	(	LIS3DH_ODR_T	odr = `LIS3DH_ODR_100HZ`,
		LIS3DH_FS_T	fs = `LIS3DH_FS_2G`,
		bool	high_res = `true`
	)

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

odr	One of the LIS3DH_ODR_T values. The default is LIS3DH_ODR_100HZ
fs	One of the LIS3DH_FS_T values. The default is LIS3DH_FS_2G
high_res	true to enable high resolution mode, false to disable. The default is true.

Exceptions

std::runtime_error on failure

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void enableAxes	(	bool	x_axis_enable,
		bool	y_axis_enable,
		bool	z_axis_enable
	)

Enable or disable specific axes. init() enables all three by default.

Parameters

x_axis_enable	true to enable X axis, false to disable
y_axis_enable	true to enable Y axis, false to disable
z_axis_enable	true to enable Z axis, false to disable

Exceptions

std::runtime_error on failure

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void enableBDUMode ( bool bdu_enable )

Enable or disable Block Data Update (BDU) mode.

Parameters

bdu_enable true to enable BDU mode, false to disable

Exceptions

std::runtime_error on failure

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void enableLPMode ( bool lp_enable )

Enable or disable Low Power (LP) mode. Checks if mutually exclusive High Resolution (HR) mode is enabled and bails out if yes.

Parameters

lp_enable true to enable LP mode, false to disable

Exceptions

std::runtime_error on failure

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void enableHRMode ( bool hr_enable )

Enable or disable High Resolution (HR) mode. Checks if mutually exclusive Low Power (LP) mode is enabled and bails out if yes.

Parameters

hr_enable true to enable HR mode, false to disable

Exceptions

std::runtime_error on failure

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void enableNormalMode ( )

Enable Normal mode by explicitly disabling LP and HR ones. Note that there's no "disable" part as it's generally unknown, which mode we were in previously. To get out of Normal mode, just enable HR or LP one.

Exceptions

std::runtime_error on failure

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void enableHPFiltering ( bool filter )

Enable high pass filtering of the accelerometer axis data. init() disables this by default. 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 enableInterruptLatching	(	bool	int1_latch,
		bool	int2_latch
	)

Enable or disable interrupt latching for INT1 and INT2. See the datasheet for details.

Parameters

int1_latch	true to enable latching for INT1, false to disable
int2_latch	true to enable latching for INT2, false to disable

Exceptions

std::runtime_error on failure

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void enableADC ( bool adc_enable )

Enable or disable built-in Analog-to-Digital Converter (ADC).

Parameters

adc_enable true to enable ADC, false to disable

Exceptions

std::runtime_error on failure

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void enableTemperature ( bool temperature_enable )

Enable or disable built-in temperature sensor. It depends on ADC being enabled, so we enable it unconditionally. See datasheet for details.

Parameters

temperature_enable true to enable temp sensor, false to disable

Exceptions

std::runtime_error on failure

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void setODR ( LIS3DH_ODR_T odr )

Set the output data rate (ODR) of the device

Parameters

odr	One of the LIS3DH_ODR_T values

Exceptions

std::runtime_error on failure

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void setFullScale ( LIS3DH_FS_T fs )

Set the full scale (FS) of the device. This device supports a full scale of 2, 4, 8 and 16G.

Parameters

fs	One of the LIS3DH_FS_T values

Exceptions

std::runtime_error on failure

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void setInterruptActiveHigh ( bool high )

Indicate whether INT1 and INT2 interrupts should be active high (default) or active low. See the datasheet for details.

Parameters

high	true for active high, false for active low

Exceptions

std::runtime_error on failure

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void setInt1Config ( uint8_t cfg )

Set interrupt 1 configuration. See the datasheet for details.

Parameters

cfg	A bitmask of values from LIS3DH_CTRL_REG3_BITS_T

Exceptions

std::runtime_error on failure

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void setInt2Config ( uint8_t cfg )

Set interrupt 2 configuration. See the datasheet for details.

Parameters

cfg	A bitmask of values from LIS3DH_CTRL_REG6_BITS_T

Exceptions

std::runtime_error on failure

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uint8_t readReg ( uint8_t reg )

Read a register

Parameters

reg	The register to read

Returns: The value of the register

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

Read contiguous registers into a buffer

Parameters

reg	The register to start the read from
buffer	The buffer to store the results
len	The number of registers to read

Returns: The number of bytes read

Exceptions

std::runtime_error on failure

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void writeReg	(	uint8_t	reg,
		uint8_t	val
	)

Write to a register

Parameters

reg	The register to write to
val	The value to write

Exceptions

std::runtime_error on failure

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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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uint8_t getStatus ( )

Return the contents of the status register

Returns: A bitmask of values from LIS3DH_STATUS_REG_BITS_T

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uint8_t getStatusAux ( )

Return the contents of the status aux register

Returns: A bitmask of values from LIS3DH_STATUS_REG_AUX_BITS_T

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void installISR	(	LIS3DH_INTERRUPT_PINS_T	intr,
		int	gpio,
		mraa::Edge	level,
		void()(void )	isr,
		void *	arg
	)

Install an interrupt handler

Parameters

intr	One of the LIS3DH_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