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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 FeatureTemperature(Feature):
"""The feature handles the data coming from a temperature sensor.
Data is two bytes long and has one decimal digit.
"""
FEATURE_NAME = "Temperature"
FEATURE_UNIT = "C" #"\u2103" # Celsius degrees.
FEATURE_DATA_NAME = "Temperature"
DATA_MAX = 100
DATA_MIN = 0
FEATURE_FIELDS = Field(
FEATURE_DATA_NAME,
FEATURE_UNIT,
FieldType.Float,
DATA_MAX,
DATA_MIN)
DATA_LENGTH_BYTES = 2
SCALE_FACTOR = 10.0
[docs] def __init__(self, node):
"""Constructor.
Args:
node (:class:`blue_st_sdk.node.Node`): Node that will send data to
this feature.
"""
super(FeatureTemperature, self).__init__(
self.FEATURE_NAME, node, [self.FEATURE_FIELDS])
return ExtractedData(sample, self.DATA_LENGTH_BYTES)
[docs] @classmethod
def get_temperature(self, sample):
"""Get the temperature value from a sample.
Args:
sample (:class:`blue_st_sdk.feature.Sample`): Sample data.
Returns:
float: The temperature value if the data array is valid, <nan>
otherwise.
"""
if sample is not None:
if sample._data:
if sample._data[0] is not None:
return float(sample._data[0])
return float('nan')
[docs] def read_temperature(self):
"""Read the temperature value.
Returns:
float: The temperature value if the read operation is successful,
<nan> 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 FeatureTemperature.get_temperature(self._get_sample())
except (BlueSTInvalidOperationException, BlueSTInvalidDataException) as e:
raise e