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# COPYRIGHT(c) 2018 STMicroelectronics #
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# IMPORT
from blue_st_sdk.feature import Feature
from blue_st_sdk.feature import Sample
from blue_st_sdk.feature import ExtractedData
from blue_st_sdk.features.field import Field
from blue_st_sdk.features.field import FieldType
from blue_st_sdk.utils.number_conversion import LittleEndian
from blue_st_sdk.utils.blue_st_exceptions import BlueSTInvalidOperationException
from blue_st_sdk.utils.blue_st_exceptions import BlueSTInvalidDataException
# CLASSES
[docs]class FeatureAccelerometer(Feature):
"""The feature handles the data coming from an accelerometer sensor.
Data is six bytes long and has no decimal digits.
"""
FEATURE_NAME = "Accelerometer"
FEATURE_UNIT = "mg"
FEATURE_DATA_NAME = ["X", "Y", "Z"]
DATA_MAX = +2000
DATA_MIN = -2000
X_INDEX = 0
Y_INDEX = 1
Z_INDEX = 2
FEATURE_X_FIELD = Field(
FEATURE_DATA_NAME[X_INDEX],
FEATURE_UNIT,
FieldType.Int16,
DATA_MAX,
DATA_MIN)
FEATURE_Y_FIELD = Field(
FEATURE_DATA_NAME[Y_INDEX],
FEATURE_UNIT,
FieldType.Int16,
DATA_MAX,
DATA_MIN)
FEATURE_Z_FIELD = Field(
FEATURE_DATA_NAME[Z_INDEX],
FEATURE_UNIT,
FieldType.Int16,
DATA_MAX,
DATA_MIN)
DATA_LENGTH_BYTES = 6
[docs] def __init__(self, node):
"""Constructor.
Args:
node (:class:`blue_st_sdk.node.Node`): Node that will send data to
this feature.
"""
super(FeatureAccelerometer, self).__init__(
self.FEATURE_NAME, node, [self.FEATURE_X_FIELD,
self.FEATURE_Y_FIELD,
self.FEATURE_Z_FIELD])
return ExtractedData(sample, self.DATA_LENGTH_BYTES)
[docs] @classmethod
def get_accelerometer_x(self, sample):
"""Get the accererometer value on the X axis from a sample.
Args:
sample (:class:`blue_st_sdk.feature.Sample`): Sample data.
Returns:
float: The accelerometer value on the X axis if the data array is
valid, <nan> otherwise.
"""
if sample is not None:
if sample._data:
if sample._data[self.X_INDEX] is not None:
return float(sample._data[self.X_INDEX])
return float('nan')
[docs] @classmethod
def get_accelerometer_y(self, sample):
"""Get the accererometer value on the Y axis from a sample.
Args:
sample (:class:`blue_st_sdk.feature.Sample`): Sample data.
Returns:
float: The accelerometer value on the Y axis if the data array is
valid, <nan> otherwise.
"""
if sample is not None:
if sample._data:
if sample._data[self.Y_INDEX] is not None:
return float(sample._data[self.Y_INDEX])
return float('nan')
[docs] @classmethod
def get_accelerometer_z(self, sample):
"""Get the accererometer value on the Z axis from a sample.
Args:
sample (:class:`blue_st_sdk.feature.Sample`): Sample data.
Returns:
float: The accelerometer value on the Z axis if the data array is
valid, <nan> otherwise.
"""
if sample is not None:
if sample._data:
if sample._data[self.Z_INDEX] is not None:
return float(sample._data[self.Z_INDEX])
return float('nan')
[docs] def read_accelerometer(self):
"""Read the accelerometer values.
Returns:
list: The accelerometer values on the three axis if the read
operation is successful, <nan> values otherwise.
Raises:
:exc:`blue_st_sdk.utils.blue_st_exceptions.BlueSTInvalidOperationException`
is raised if the feature is not enabled or the operation
required is not supported.
:exc:`blue_st_sdk.utils.blue_st_exceptions.BlueSTInvalidDataException`
if the data array has not enough data to read.
"""
try:
self._read_data()
return [FeatureAccelerometer.get_accelerometer_x(self._get_sample()),
FeatureAccelerometer.get_accelerometer_y(self._get_sample()),
FeatureAccelerometer.get_accelerometer_z(self._get_sample())]
except (BlueSTInvalidOperationException, BlueSTInvalidDataException) as e:
raise e