├── .gitignore
├── requirements.txt
└── co2mon.py


/.gitignore:
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1 | .idea/
2 | *.iml
3 | 


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/requirements.txt:
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1 | hidraw-pure
2 | graphitesend
3 | flask


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/co2mon.py:
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  1 | #!/usr/bin/python3
  2 | 
  3 | import os
  4 | from typing import BinaryIO, Union
  5 | 
  6 | import hidraw
  7 | 
  8 | _cstate = b"Htemp99e"
  9 | _shuffle = (2, 4, 0, 7, 1, 6, 5, 3)
 10 | _ctmp = bytes([((_cstate[i] >> 4) | (_cstate[i] << 4)) & 0xff for i in range(8)])
 11 | 
 12 | 
 13 | # https://github.com/poempelfox/co2sensorsw/blob/master/co2sensord.c
 14 | def _decrypt(buf: bytes, key: bytes) -> bytes:
 15 |     assert len(buf) == 8
 16 |     assert len(key) == 8
 17 |     phase1 = bytearray(8)
 18 |     for j in range(8):
 19 |         phase1[_shuffle[j]] = buf[j]
 20 |     phase2 = [phase1[i] ^ key[i] for i in range(8)]
 21 |     phase3 = [(phase2[i] >> 3) | ((phase2[(i + 7) % 8] << 5) & 0xff) for i in range(8)]
 22 |     out = [(0x100 + phase3[i] - _ctmp[i]) & 0xff for i in range(8)]
 23 |     return bytes(out)
 24 | 
 25 | 
 26 | def init_sensor(dev: hidraw.HIDRaw, key: bytes):
 27 |     assert len(key) == 8
 28 |     dev.sendFeatureReport(key)
 29 | 
 30 | 
 31 | def read_sensor(dev: BinaryIO, key: bytes):
 32 |     buf = dev.read(8)
 33 |     return _parse(_decrypt(buf, key))
 34 | 
 35 | 
 36 | def generate_key() -> bytes:
 37 |     return os.urandom(8)
 38 | 
 39 | 
 40 | class Temperature:
 41 |     def __init__(self, raw: int):
 42 |         self.raw = raw
 43 | 
 44 |     def kelvin(self) -> float:
 45 |         return self.raw / 16.0
 46 | 
 47 |     def celsius(self) -> float:
 48 |         return self.kelvin() - 273.15
 49 | 
 50 |     def __repr__(self):
 51 |         return "Temperature(%s = %s°C)" % (self.raw, self.celsius())
 52 | 
 53 | 
 54 | class CO2:
 55 |     def __init__(self, raw: int):
 56 |         self.raw = raw
 57 | 
 58 |     def ppm(self) -> int:
 59 |         return self.raw
 60 | 
 61 |     def __repr__(self):
 62 |         return "CO2(%s ppm)" % self.ppm()
 63 | 
 64 | 
 65 | class Unknown:
 66 |     # noinspection PyShadowingBuiltins
 67 |     def __init__(self, type: int, raw: int):
 68 |         self.type = type
 69 |         self.raw = raw
 70 | 
 71 |     def __repr__(self):
 72 |         return "Unknown(type=0x%x, %s)" % (self.type, self.raw)
 73 | 
 74 | 
 75 | class FormatError(IOError):
 76 |     def __init__(self, msg):
 77 |         super(FormatError, self).__init__(msg)
 78 | 
 79 | 
 80 | def _parse(decrypted: bytes) -> Union[CO2, Temperature, Unknown]:
 81 |     expected_sum = sum(decrypted[0:3]) & 0xff
 82 |     if expected_sum != decrypted[3]:
 83 |         raise FormatError("Checksum mismatch: '%s'" % decrypted)
 84 |     if decrypted[4:] != b"\x0d\x00\x00\x00":
 85 |         raise FormatError("Padding mismatch: '%s'" % decrypted)
 86 |     raw = (decrypted[1] << 8) | decrypted[2]
 87 |     if decrypted[0] == 0x50:
 88 |         return CO2(raw)
 89 |     elif decrypted[0] == 0x42:
 90 |         return Temperature(raw)
 91 |     else:
 92 |         return Unknown(decrypted[0], raw)
 93 | 
 94 | 
 95 | def _main():
 96 |     import graphitesend
 97 |     import sys
 98 |     import argparse
 99 | 
100 |     parser = argparse.ArgumentParser()
101 |     parser.add_argument("file")
102 |     parser.add_argument("--graphite-server")
103 |     parser.add_argument("--graphite-id", default='0')
104 |     parser.add_argument("--http-host", default='127.0.0.1')
105 |     parser.add_argument("--http-port", type=int)
106 |     args = parser.parse_args()
107 | 
108 |     graphite = args.graphite_server is not None
109 |     if graphite:
110 |         graphitesend.init(graphite_server=args.graphite_server, prefix="co2mon." + args.graphite_id,
111 |                           system_name="")
112 | 
113 |     state = {}
114 | 
115 |     if args.http_port:
116 |         import flask
117 |         import threading
118 |         app = flask.Flask("co2mon")
119 | 
120 |         @app.route("/")
121 |         def show_state():
122 |             return flask.jsonify(state)
123 | 
124 |         def run():
125 |             app.run(host=args.http_host, port=args.http_port)
126 | 
127 |         threading.Thread(target=run, daemon=True).start()
128 | 
129 |     with open(sys.argv[1], "r+b") as dev:
130 |         key = generate_key()
131 |         hid = hidraw.HIDRaw(dev.fileno())
132 |         init_sensor(hid, key)
133 |         while True:
134 |             data = read_sensor(dev, key)
135 |             if type(data) == CO2:
136 |                 if graphite:
137 |                     graphitesend.send("co2", data.ppm())
138 |                 state["co2"] = data.ppm()
139 |             elif type(data) == Temperature:
140 |                 if graphite:
141 |                     graphitesend.send("temperature", data.celsius())
142 |                 state["temperature"] = data.celsius()
143 | 
144 | 
145 | if __name__ == '__main__':
146 |     _main()
147 | 


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