Initial commit

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/

LICENSE

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+MIT License
+
+Copyright (c) 2018 Michael Smith
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# py-cayenne-lpp-decoder
+Cayenne Low Power Payload decoder written in Python.
+See [Cayenne Low Power Payload Documentation](https://mydevices.com/cayenne/docs/lora/#lora-cayenne-low-power-payload) for more information.
+
+The decoder expects a base64 encoded payload string, commonly used in LoRaWAN implementations.
+
+## Usage
+
+```python
+>>> import cayennelpp
+>>> print(cayennelpp.lppdecode('A2cBEAVnAP8='))
+[{'channel': 3, 'type': 'Temperature Sensor', 'value': 27.2}, {'channel': 5, 'type': 'Temperature Sensor',
+'value': 25.5}]
+
+```

cayennelpp.py

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+# -*- coding: utf-8 -*-
+import base64
+import binascii
+
+
+def one_per_bit_unsigned(data):
+    return int.from_bytes(data, byteorder='big', signed=False)
+
+
+def point_zero_one_per_bit_signed(data):
+    return int.from_bytes(data, byteorder='big', signed=True) / 100
+
+
+def temperature(data):
+    return int.from_bytes(data, byteorder='big', signed=True) / 10
+
+
+def humidity(data):
+    return int.from_bytes(data, byteorder='big', signed=False) / 2
+
+
+def accelerometer(data):
+    x = int.from_bytes(data[:2], byteorder='big', signed=True) / 1000
+    y = int.from_bytes(data[2:4], byteorder='big', signed=True) / 1000
+    z = int.from_bytes(data[4:6], byteorder='big', signed=True) / 1000
+
+    return {'x': x, 'y': y, 'z': z}
+
+
+def barometer(data):
+    return int.from_bytes(data, byteorder='big', signed=False) / 10
+
+
+def gyrometer(data):
+    x = int.from_bytes(data[:2], byteorder='big', signed=True) / 100
+    y = int.from_bytes(data[2:4], byteorder='big', signed=True) / 100
+    z = int.from_bytes(data[4:6], byteorder='big', signed=True) / 100
+
+    return {'x': x, 'y': y, 'z': z}
+
+
+def gps_location(data):
+    lat = int.from_bytes(data[:3], byteorder='big', signed=True) / 10000
+    lon = int.from_bytes(data[3:6], byteorder='big', signed=True) / 10000
+    alt = int.from_bytes(data[6:], byteorder='big', signed=True) / 100
+
+    return {'lat': lat, 'lon': lon, 'alt': alt}
+
+
+DATA_TYPES = {
+    b'\x00': {
+        "name": "Digital Input",
+        "size": 1,
+        "decoder": one_per_bit_unsigned
+    },
+    b'\x01': {
+        "name": "Digital Output",
+        "size": 1,
+        "decoder": one_per_bit_unsigned
+    },
+    b'\x02': {
+        "name": "Analog Input",
+        "size": 2,
+        "decoder": point_zero_one_per_bit_signed
+    },
+    b'\x03': {
+        "name": "Analog Output",
+        "size": 2,
+        "decoder": point_zero_one_per_bit_signed
+    },
+    b'\x65': {
+        "name": "Illuminance Sensor",
+        "size": 2,
+        "decoder": one_per_bit_unsigned
+    },
+    b'\x66': {
+        "name": "Presence Sensor",
+        "size": 1,
+        "decoder": one_per_bit_unsigned
+    },
+    b'\x67': {
+        "name": "Temperature Sensor",
+        "size": 2,
+        "decoder": temperature
+    },
+    b'\x68': {
+        "name": "Humidity Sensor",
+        "size": 1,
+        "decoder": humidity
+    },
+    b'\x71': {
+        "name": "Accelerometer",
+        "size": 6,
+        "decoder": accelerometer
+    },
+    b'\x73': {
+        "name": "Barometer",
+        "size": 2,
+        "decoder": barometer
+    },
+    b'\x86': {
+        "name": "Gyrometer",
+        "size": 6,
+        "decoder": gyrometer
+    },
+    b'\x88': {
+        "name": "GPS Location",
+        "size": 9,
+        "decoder": gps_location
+    },
+}
+
+
+def lppdecode(base64_string):
+    cursor = 0
+    result = []
+    payload = base64.b64decode(base64_string)
+
+    while cursor < len(payload):
+        data_channel = int.from_bytes(payload[cursor:cursor + 1],
+                                      byteorder='big')
+        cursor += 1
+        data_type = payload[cursor:cursor + 1]
+        if data_type in DATA_TYPES:
+            cursor += 1
+            name = DATA_TYPES[data_type]['name']
+            size = DATA_TYPES[data_type]['size']
+            decoder = DATA_TYPES[data_type]['decoder']
+            result.append(
+                {"channel": data_channel,
+                 "type": name,
+                 "value": decoder(payload[cursor:cursor + size])})
+            cursor += size
+        else:
+            # Unknown LPP data type
+            result = None
+            break
+
+    return result

test_decoder.py

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+# -*- coding: utf-8 -*-
+import unittest
+import cayennelpp
+
+
+class DecoderTestCase(unittest.TestCase):
+    """Unit tests for Cayenne LPP decoder."""
+
+    def test_two_temperature_sensors(self):
+        result = cayennelpp.lppdecode('A2cBEAVnAP8=')
+        self.assertEqual(result,
+                         [{'channel': 3,
+                           'type': 'Temperature Sensor',
+                           'value': 27.2},
+                          {'channel': 5,
+                           'type': 'Temperature Sensor',
+                           'value': 25.5}])
+
+    def test_temperature_and_acceleration_sensors(self):
+        result = cayennelpp.lppdecode('AWf/1wZxBNL7LgAA')
+        self.assertEqual(result,
+                         [{'channel': 1,
+                           'type': 'Temperature Sensor',
+                           'value': -4.1},
+                          {'channel': 6,
+                           'type': 'Accelerometer',
+                           'value': {'x': 1.234, 'y': -1.234, 'z': 0.0}}])
+
+    def test_decode_gps(self):
+        result = cayennelpp.lppdecode('AYgGdl/ylgoAA+g=')
+        self.assertEqual(result,
+                         [{'channel': 1,
+                           'type': 'GPS Location',
+                           'value': {'lat': 42.3519,
+                                     'lon': -87.9094,
+                                     'alt': 10.0}}])
+
+    def test_decode_all_previous_tests_combined(self):
+        result = cayennelpp.lppdecode(
+            'AWcBEAVnAP8CZ//XA3EE0vsuAAAEiAZ2X/KWCgAD6A==')
+        self.assertEqual(result,
+                         [{'channel': 1,
+                           'type': 'Temperature Sensor',
+                           'value': 27.2},
+                          {'channel': 5,
+                           'type': 'Temperature Sensor',
+                           'value': 25.5},
+                          {'channel': 2,
+                           'type': 'Temperature Sensor',
+                           'value': -4.1},
+                          {'channel': 3,
+                           'type': 'Accelerometer',
+                           'value': {'x': 1.234, 'y': -1.234, 'z': 0.0}},
+                          {'channel': 4,
+                           'type': 'GPS Location',
+                           'value': {'lat': 42.3519,
+                                     'lon': -87.9094,
+                                     'alt': 10.0}}])
+
+    def test_decode_unknown_lpp_data_type(self):
+        result = cayennelpp.lppdecode('AQQBEA==')
+        self.assertEqual(result, None)
+
+
+if __name__ == '__main__':
+    unittest.main()