AccelerometerService

Using the Pebble accelerometer. More...

Collaboration diagram for AccelerometerService:

Typedefs
typedef void(*	AccelDataHandler) (AccelData *data, uint32_t num_samples)
typedef void(*	AccelRawDataHandler) (AccelRawData *data, uint32_t num_samples, uint64_t timestamp)
typedef void(*	AccelTapHandler) (AccelAxisType axis, int32_t direction)
typedef void(*	AccelDataHandler) (AccelData *data, uint32_t num_samples)
typedef void(*	AccelRawDataHandler) (AccelRawData *data, uint32_t num_samples, uint64_t timestamp)
typedef void(*	AccelTapHandler) (AccelAxisType axis, int32_t direction)

Enumerations
enum	AccelAxisType {   ACCEL_AXIS_X = 0, ACCEL_AXIS_Y = 1, ACCEL_AXIS_Z = 2, ACCEL_AXIS_X = 0,   ACCEL_AXIS_Y = 1, ACCEL_AXIS_Z = 2 }
	Enumerated values defining the three accelerometer axes. More...
enum	AccelSamplingRate {   ACCEL_SAMPLING_10HZ = 10, ACCEL_SAMPLING_25HZ = 25, ACCEL_SAMPLING_50HZ = 50, ACCEL_SAMPLING_100HZ = 100,   ACCEL_SAMPLING_10HZ = 10, ACCEL_SAMPLING_25HZ = 25, ACCEL_SAMPLING_50HZ = 50, ACCEL_SAMPLING_100HZ = 100 }
	Valid accelerometer sampling rates, in Hz. More...
enum	AccelAxisType {   ACCEL_AXIS_X = 0, ACCEL_AXIS_Y = 1, ACCEL_AXIS_Z = 2, ACCEL_AXIS_X = 0,   ACCEL_AXIS_Y = 1, ACCEL_AXIS_Z = 2 }
	Enumerated values defining the three accelerometer axes. More...
enum	AccelSamplingRate {   ACCEL_SAMPLING_10HZ = 10, ACCEL_SAMPLING_25HZ = 25, ACCEL_SAMPLING_50HZ = 50, ACCEL_SAMPLING_100HZ = 100,   ACCEL_SAMPLING_10HZ = 10, ACCEL_SAMPLING_25HZ = 25, ACCEL_SAMPLING_50HZ = 50, ACCEL_SAMPLING_100HZ = 100 }
	Valid accelerometer sampling rates, in Hz. More...

Functions
struct	__attribute__ ((__packed__))
	A single accelerometer sample for all three axes. More...
int	accel_service_peek (AccelData *data)
int	accel_service_set_sampling_rate (AccelSamplingRate rate)
int	accel_service_set_samples_per_update (uint32_t num_samples)
void	accel_data_service_subscribe (uint32_t samples_per_update, AccelDataHandler handler)
void	accel_data_service_unsubscribe (void)
void	accel_tap_service_subscribe (AccelTapHandler handler)
void	accel_tap_service_unsubscribe (void)
void	accel_raw_data_service_subscribe (uint32_t samples_per_update, AccelRawDataHandler handler)

Variables
	AccelData
	AccelRawData
	AccelData
	AccelRawData

Detailed Description

Using the Pebble accelerometer.

The AccelerometerService enables the Pebble accelerometer to detect taps, perform measures at a given frequency, and transmit samples in batches to save CPU time and processing.

For available code samples, see the feature-accel-discs example app.

Typedef Documentation

AccelDataHandler [1/2]

typedef void(* AccelDataHandler) (AccelData *data, uint32_t num_samples)

Callback type for accelerometer data events

Parameters

data	Pointer to the collected accelerometer samples.
num_samples	the number of samples stored in data.

AccelDataHandler [2/2]

typedef void(* AccelDataHandler) (AccelData *data, uint32_t num_samples)

Callback type for accelerometer data events

Parameters

data	Pointer to the collected accelerometer samples.
num_samples	the number of samples stored in data.

AccelRawDataHandler [1/2]

typedef void(* AccelRawDataHandler) (AccelRawData *data, uint32_t num_samples, uint64_t timestamp)

Callback type for accelerometer raw data events

Parameters

data	Pointer to the collected accelerometer samples.
num_samples	the number of samples stored in data.
timestamp	the timestamp, in ms, of the first sample.

AccelRawDataHandler [2/2]

typedef void(* AccelRawDataHandler) (AccelRawData *data, uint32_t num_samples, uint64_t timestamp)

Callback type for accelerometer raw data events

Parameters

data	Pointer to the collected accelerometer samples.
num_samples	the number of samples stored in data.
timestamp	the timestamp, in ms, of the first sample.

AccelTapHandler [1/2]

typedef void(* AccelTapHandler) (AccelAxisType axis, int32_t direction)

Callback type for accelerometer tap events

Parameters

axis	the axis on which a tap was registered (x, y, or z)
direction	the direction (-1 or +1) of the tap

AccelTapHandler [2/2]

typedef void(* AccelTapHandler) (AccelAxisType axis, int32_t direction)

Callback type for accelerometer tap events

Parameters

axis	the axis on which a tap was registered (x, y, or z)
direction	the direction (-1 or +1) of the tap

Enumeration Type Documentation

AccelAxisType [1/2]

enum AccelAxisType

Enumerated values defining the three accelerometer axes.

Enumerator
ACCEL_AXIS_X	Accelerometer's X axis. The positive direction along the X axis goes toward the right of the watch.
ACCEL_AXIS_Y	Accelerometer's Y axis. The positive direction along the Y axis goes toward the top of the watch.
ACCEL_AXIS_Z	Accelerometer's Z axis. The positive direction along the Z axis goes vertically out of the watchface.
ACCEL_AXIS_X	Accelerometer's X axis. The positive direction along the X axis goes toward the right of the watch.
ACCEL_AXIS_Y	Accelerometer's Y axis. The positive direction along the Y axis goes toward the top of the watch.
ACCEL_AXIS_Z	Accelerometer's Z axis. The positive direction along the Z axis goes vertically out of the watchface.

AccelAxisType [2/2]

enum AccelAxisType

Enumerated values defining the three accelerometer axes.

Enumerator
ACCEL_AXIS_X	Accelerometer's X axis. The positive direction along the X axis goes toward the right of the watch.
ACCEL_AXIS_Y	Accelerometer's Y axis. The positive direction along the Y axis goes toward the top of the watch.
ACCEL_AXIS_Z	Accelerometer's Z axis. The positive direction along the Z axis goes vertically out of the watchface.
ACCEL_AXIS_X	Accelerometer's X axis. The positive direction along the X axis goes toward the right of the watch.
ACCEL_AXIS_Y	Accelerometer's Y axis. The positive direction along the Y axis goes toward the top of the watch.
ACCEL_AXIS_Z	Accelerometer's Z axis. The positive direction along the Z axis goes vertically out of the watchface.

AccelSamplingRate [1/2]

enum AccelSamplingRate

Valid accelerometer sampling rates, in Hz.

Enumerator
ACCEL_SAMPLING_10HZ	10 HZ sampling rate
ACCEL_SAMPLING_25HZ	25 HZ sampling rate [Default]
ACCEL_SAMPLING_50HZ	50 HZ sampling rate
ACCEL_SAMPLING_100HZ	100 HZ sampling rate
ACCEL_SAMPLING_10HZ	10 HZ sampling rate
ACCEL_SAMPLING_25HZ	25 HZ sampling rate [Default]
ACCEL_SAMPLING_50HZ	50 HZ sampling rate
ACCEL_SAMPLING_100HZ	100 HZ sampling rate

AccelSamplingRate [2/2]

enum AccelSamplingRate

Valid accelerometer sampling rates, in Hz.

Enumerator
ACCEL_SAMPLING_10HZ	10 HZ sampling rate
ACCEL_SAMPLING_25HZ	25 HZ sampling rate [Default]
ACCEL_SAMPLING_50HZ	50 HZ sampling rate
ACCEL_SAMPLING_100HZ	100 HZ sampling rate
ACCEL_SAMPLING_10HZ	10 HZ sampling rate
ACCEL_SAMPLING_25HZ	25 HZ sampling rate [Default]
ACCEL_SAMPLING_50HZ	50 HZ sampling rate
ACCEL_SAMPLING_100HZ	100 HZ sampling rate

Function Documentation

__attribute__()

struct __attribute__

(

(__packed__)

)

A single accelerometer sample for all three axes.

A single accelerometer sample for all three axes including timestamp and vibration rumble status.

Data structure for one serialized key/value tuple

Note

The structure is variable length! The length depends on the value data that the tuple contains.

acceleration along the x axis

acceleration along the y axis

acceleration along the z axis

true if the watch vibrated when this sample was collected

timestamp, in milliseconds

acceleration along the x axis

acceleration along the y axis

acceleration along the z axis

The key

The type of data that the .value fields contains.

The length of .value in bytes

The value itself.

The different union fields are provided for convenience, avoiding the need for manual casts.

Note

The array length is of incomplete length on purpose, to facilitate variable length data and because a data length of zero is valid.

Important: The integers are little endian!

The byte array value. Valid when .type is TUPLE_BYTE_ARRAY.

The C-string value. Valid when .type is TUPLE_CSTRING.

The 8-bit unsigned integer value. Valid when .type is TUPLE_UINT and .length is 1 byte.

The 16-bit unsigned integer value. Valid when .type is TUPLE_UINT and .length is 2 byte.

The 32-bit unsigned integer value. Valid when .type is TUPLE_UINT and .length is 4 byte.

The 8-bit signed integer value. Valid when .type is TUPLE_INT and .length is 1 byte.

The 16-bit signed integer value. Valid when .type is TUPLE_INT and .length is 2 byte.

The 32-bit signed integer value. Valid when .type is TUPLE_INT and .length is 4 byte.

acceleration along the x axis

acceleration along the y axis

acceleration along the z axis

true if the watch vibrated when this sample was collected

timestamp, in milliseconds

acceleration along the x axis

acceleration along the y axis

acceleration along the z axis

accel_data_service_subscribe()

void accel_data_service_subscribe	(	uint32_t	samples_per_update,
		AccelDataHandler	handler
	)

Subscribe to the accelerometer data event service. Once subscribed, the handler gets called every time there are new accelerometer samples available.

Note

Cannot use accel_service_peek() when subscribed to accelerometer data events.

Parameters

handler	A callback to be executed on accelerometer data events
samples_per_update	the number of samples to buffer, between 0 and 25.

accel_data_service_unsubscribe()

void accel_data_service_unsubscribe

(

void

)

Unsubscribe from the accelerometer data event service. Once unsubscribed, the previously registered handler will no longer be called.

accel_raw_data_service_subscribe()

void accel_raw_data_service_subscribe	(	uint32_t	samples_per_update,
		AccelRawDataHandler	handler
	)

Subscribe to the accelerometer raw data event service. Once subscribed, the handler gets called every time there are new accelerometer samples available.

Note

Cannot use accel_service_peek() when subscribed to accelerometer data events.

Parameters

handler	A callback to be executed on accelerometer data events
samples_per_update	the number of samples to buffer, between 0 and 25.

accel_service_peek()

int accel_service_peek

(

AccelData *

data

)

Peek at the last recorded reading.

Parameters

[out]

data

a pointer to a pre-allocated AccelData item

Note

Cannot be used when subscribed to accelerometer data events.

Returns

-1 if the accel is not running

-2 if subscribed to accelerometer events.

accel_service_set_samples_per_update()

int accel_service_set_samples_per_update

(

uint32_t

num_samples

)

Change the number of samples buffered between each accelerometer data event

Parameters

num_samples

the number of samples to buffer, between 0 and 25.

accel_service_set_sampling_rate()

int accel_service_set_sampling_rate

(

AccelSamplingRate

rate

)

Change the accelerometer sampling rate.

Parameters

rate	The sampling rate in Hz (10Hz, 25Hz, 50Hz, and 100Hz possible)

accel_tap_service_subscribe()

void accel_tap_service_subscribe

(

AccelTapHandler

handler

)

Subscribe to the accelerometer tap event service. Once subscribed, the handler gets called on every tap event emitted by the accelerometer.

Parameters

handler

A callback to be executed on tap event

accel_tap_service_unsubscribe()

void accel_tap_service_unsubscribe

(

void

)

Unsubscribe from the accelerometer tap event service. Once unsubscribed, the previously registered handler will no longer be called.