Motion Sensor

General Description

Basic set of APIs for interacting with the BMI160 motion sensor.

This provides basic initialization and access to to the basic accelerometer & gyroscope data. It also provides access to the base BMI160 driver for full control. For more information about the motion sensor, see: https://github.com/BoschSensortec/BMI160_driver

Note

Currently, this library only supports being used for a single instance of this device.

BMI160 support requires delays. If the RTOS_AWARE component is set or CY_RTOS_AWARE is defined, the HAL driver will defer to the RTOS for delays. Because of this, it is not safe to call any functions other than mtb_bmi160_init_i2c until after the RTOS scheduler has started.

There is a known issue with the BMI160 endianness detection. Any code referencing the structures defined in the BMI160 driver should have this header file, mtb_bmi160.h, first in any includes.

Code snippets

Snippet 1: Simple initialization with I2C.

The following snippet initializes an I2C instance and the BMI160, then reads from the BMI160.

    /* Initialize I2C and BMI160 */
    result = cyhal_i2c_init(&i2c_instance, PIN_IMU_I2C_SDA, PIN_IMU_I2C_SCL, NULL);
    result = mtb_bmi160_init_i2c(&imu, &i2c_instance, MTB_BMI160_DEFAULT_ADDRESS);
    /* Read data from BMI160 */
    result = mtb_bmi160_read(&imu, &imu_data);

Snippet 2: BMI160 interrupt configuration.

The following snippet demonstrates how to configure a BMI160 interrupt.

    /* Populate BMI160 interrupt configuration structure and configure interrupt */
    struct bmi160_int_settg intsettings;
    cy_rslt_t result;
 
    intsettings.int_channel = BMI160_INT_CHANNEL_1;
    intsettings.int_type = BMI160_ACC_ANY_MOTION_INT;
    intsettings.int_pin_settg.output_en = BMI160_ENABLE;
    intsettings.int_pin_settg.output_mode = 0;
    intsettings.int_pin_settg.output_type = 0;
    intsettings.int_pin_settg.edge_ctrl = 1;
    intsettings.int_pin_settg.input_en = 0;
    intsettings.int_pin_settg.latch_dur = 0;
 
    intsettings.int_type_cfg.acc_any_motion_int.anymotion_en = 1;
    intsettings.int_type_cfg.acc_any_motion_int.anymotion_x = 1;
    intsettings.int_type_cfg.acc_any_motion_int.anymotion_y = 1;
    intsettings.int_type_cfg.acc_any_motion_int.anymotion_z = 1;
    intsettings.int_type_cfg.acc_any_motion_int.anymotion_dur = 0;
    intsettings.int_type_cfg.acc_any_motion_int.anymotion_thr = 20;
 
    intsettings.fifo_full_int_en = 0;
    intsettings.fifo_wtm_int_en = 0;
 
    result = mtb_bmi160_config_int(obj, &intsettings, PIN_IMU_INT_1, CYHAL_ISR_PRIORITY_DEFAULT,
                                   CYHAL_GPIO_IRQ_FALL, (cyhal_gpio_event_callback_t)&imucallback,
                                   NULL);

Data Structures
struct	mtb_bmi160_t
	Structure holding the IMU instance specific information. More...
struct	mtb_bmi160_data_t
	Structure holding the accelerometer and gyroscope data read from the device. More...

Macros
#define	MTB_BMI160_RSLT_ERR_INSUFFICIENT_INT_PINS    (CY_RSLT_CREATE(CY_RSLT_TYPE_ERROR, CY_RSLT_MODULE_BOARD_HARDWARE_BMI160, 0x100))
	An attempt was made to configure too many gpio pins as interrupts.

Enumerations
enum	mtb_bmi160_address_t {   MTB_BMI160_DEFAULT_ADDRESS = BMI160_I2C_ADDR ,   MTB_BMI160_SECONDARY_ADDRESS = BMI160_AUX_BMM150_I2C_ADDR }
	Enumeration used for selecting I2C address.

Functions
cy_rslt_t	mtb_bmi160_init_i2c (mtb_bmi160_t *obj, cyhal_i2c_t *inst, mtb_bmi160_address_t address)
	Initialize the IMU for I2C communication. More...
cy_rslt_t	mtb_bmi160_init_spi (mtb_bmi160_t *obj, cyhal_spi_t *inst, cyhal_gpio_t spi_ss)
	Initialize the sensor for SPI communication. More...
cy_rslt_t	mtb_bmi160_config_default (mtb_bmi160_t *obj)
	Configure the motion sensor to a default mode with both accelerometer & gyroscope enabled with a nominal output data rate. More...
cy_rslt_t	mtb_bmi160_read (mtb_bmi160_t *obj, mtb_bmi160_data_t *sensor_data)
	Reads the current accelerometer & gyroscope data from the motion sensor. More...
struct bmi160_dev *	mtb_bmi160_get (mtb_bmi160_t *obj)
	Gets access to the base motion sensor data. More...
cy_rslt_t	mtb_bmi160_selftest (mtb_bmi160_t *obj)
	Performs both accelerometer and gyro self tests. More...
cy_rslt_t	mtb_bmi160_config_int (mtb_bmi160_t *obj, struct bmi160_int_settg *intsettings, cyhal_gpio_t pin, uint8_t intr_priority, cyhal_gpio_event_t event, cyhal_gpio_event_callback_t callback, void *callback_arg)
	Configure a GPIO pin as an interrupt for the BMI160. More...
void	mtb_bmi160_free (mtb_bmi160_t *obj)
	Frees up any resources allocated by the motion_sensor as part of mtb_bmi160_init_i2c(). More...

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Data Structure Documentation

mtb_bmi160_t

struct mtb_bmi160_t

Data Fields
struct bmi160_dev	sensor
_mtb_bmi160_interrupt_pin_t	intpin1
_mtb_bmi160_interrupt_pin_t	intpin2

mtb_bmi160_data_t

struct mtb_bmi160_data_t

Data Fields
struct bmi160_sensor_data	accel	Accelerometer data.
struct bmi160_sensor_data	gyro	Gyroscope data.

Function Documentation

mtb_bmi160_init_i2c()

cy_rslt_t mtb_bmi160_init_i2c	(	mtb_bmi160_t *	obj,
		cyhal_i2c_t *	inst,
		mtb_bmi160_address_t	address
	)

Initialize the IMU for I2C communication.

Then applies the default configuration settings for both the accelerometer & gyroscope. Known maximum I2C frequency of 1MHz; refer to manufacturer's datasheet for confirmation. See: mtb_bmi160_config_default()

Parameters

[in]	obj	Pointer to a BMI160 object. The caller must allocate the memory for this object but the init function will initialize its contents.
[in]	inst	I2C instance to use for communicating with the BMI160 sensor.
[in]	address	BMI160 I2C address, set by hardware implementation.

Returns

CY_RSLT_SUCCESS if properly initialized, else an error indicating what went wrong.

mtb_bmi160_init_spi()

cy_rslt_t mtb_bmi160_init_spi	(	mtb_bmi160_t *	obj,
		cyhal_spi_t *	inst,
		cyhal_gpio_t	spi_ss
	)

Initialize the sensor for SPI communication.

Then applies the default configuration settings for the accelerometer & gyroscope. NOTE: The SPI slave select pin (spi_ss) is expected to be controlled by this driver, not the SPI block itself. This allows the driver to issue multiple read/write requests back to back. See: mtb_bmi160_config_default()

Parameters

[in]	obj	Pointer to a BMI160 object. The caller must allocate the memory for this object but the init function will initialize its contents.
[in]	inst	SPI instance to use for communicating with the BMI160 sensor.
[in]	spi_ss	SPI slave select pin to use for communicating with the BMI160 sensor.

Returns

CY_RSLT_SUCCESS if properly initialized, else an error indicating what went wrong.

mtb_bmi160_config_default()

cy_rslt_t mtb_bmi160_config_default

(

mtb_bmi160_t *

obj

)

Configure the motion sensor to a default mode with both accelerometer & gyroscope enabled with a nominal output data rate.

The default values used are from the example in the BMI160 driver repository, see https://github.com/BoschSensortec/BMI160_driver

Parameters

[in]

obj

Pointer to a BMI160 object.

Returns

CY_RSLT_SUCCESS if properly initialized, else an error indicating what went wrong.

mtb_bmi160_read()

cy_rslt_t mtb_bmi160_read	(	mtb_bmi160_t *	obj,
		mtb_bmi160_data_t *	sensor_data
	)

Reads the current accelerometer & gyroscope data from the motion sensor.

Parameters

[in]	obj	Pointer to a BMI160 object.
[out]	sensor_data	The accelerometer & gyroscope data read from the motion sensor

Returns

CY_RSLT_SUCCESS if properly initialized, else an error indicating what went wrong.

mtb_bmi160_get()

struct bmi160_dev * mtb_bmi160_get

(

mtb_bmi160_t *

obj

)

Gets access to the base motion sensor data.

This allows for direct manipulation of the sensor for any desired behavior. See https://github.com/BoschSensortec/BMI160_driver for more details on the sensor.

Parameters

[in]

obj

Pointer to a BMI160 object.

Returns

pointer to the BMI160 configuration structure.

mtb_bmi160_selftest()

cy_rslt_t mtb_bmi160_selftest

(

mtb_bmi160_t *

obj

)

Performs both accelerometer and gyro self tests.

Note these tests cause a soft reset of the device and device should be reconfigured after a test. See https://github.com/BoschSensortec/BMI160_driver for more details.

Parameters

[in]

obj

Pointer to a BMI160 object.

Returns

CY_RSLT_SUCCESS if self tests pass, else an error indicating what went wrong.

mtb_bmi160_config_int()

cy_rslt_t mtb_bmi160_config_int	(	mtb_bmi160_t *	obj,
		struct bmi160_int_settg *	intsettings,
		cyhal_gpio_t	pin,
		uint8_t	intr_priority,
		cyhal_gpio_event_t	event,
		cyhal_gpio_event_callback_t	callback,
		void *	callback_arg
	)

Configure a GPIO pin as an interrupt for the BMI160.

This configures the pin as an interrupt, and calls the BMI160 interrupt configuration API with the application supplied settings structure. See https://github.com/BoschSensortec/BMI160_driver for more details.

Parameters

[in]	obj	Pointer to a BMI160 object.
[in]	intsettings	Pointer to a BMI160 interrupt settings structure.
[in]	pin	Which pin to configure as interrupt
[in]	intr_priority	The priority for NVIC interrupt events
[in]	event	The type of interrupt event
[in]	callback	The function to call when the specified event happens. Pass NULL to unregister the handler.
[in]	callback_arg	Generic argument that will be provided to the callback when called, can be NULL

Returns

CY_RSLT_SUCCESS if interrupt was successfully enabled.

mtb_bmi160_free()

void mtb_bmi160_free

(

mtb_bmi160_t *

obj

)

Frees up any resources allocated by the motion_sensor as part of mtb_bmi160_init_i2c().

Parameters

[in]

obj

Pointer to a BMI160 object.