Encode Decode Sigfox points.ipynb

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   "source": [
    "The Sigfox network allows 12 bytes per point. The PAC / id and time do not need to be included in the point payload since they are in the envelope.\n",
    "\n",
    "Format:\n",
    " * (1) Status bits\n",
    "   * (.1) Reserved\n",
    "   * (.1) Tilt\n",
    "   * (.1) Digital In Long Press\n",
    "   * (.1) TB1=1/SA4=0 (changes following fields)\n",
    "   * (.1) Battery Low\n",
    "   * (.1) GPS Good\n",
    "   * (.1) Digital In / Ignition\n",
    "   * (.1) PTO\n",
    " * (3.4) Latitude\n",
    " * (3.4) Longitude\n",
    " * (1) Speed\n",
    " * (1) Course\n",
    " * (1) Altitude\n",
    " * (1) Temperature (by 0.5 degrees) -64 -> 63"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "import struct\n",
    "import binascii\n",
    "\n",
    "def packll(latitude, longitude):\n",
    "    assert -180 <= longitude <= 180\n",
    "    assert -90 <= latitude <= 90\n",
    "    latitude = int((latitude + 180) * 600000)\n",
    "    longitude = int((longitude + 180) * 600000)\n",
    "    b0 = (latitude >> 20) & 0xff\n",
    "    b1 = (latitude >> 12) & 0xff\n",
    "    b2 = (latitude >> 4) & 0xff\n",
    "    b3 = (latitude & 0x0f) << 4\n",
    "    b3 |= (longitude >> 24) & 0x0f\n",
    "    b4 = (longitude >> 16) & 0xff\n",
    "    b5 = (longitude >> 8) & 0xff\n",
    "    b6 = longitude & 0xff\n",
    "    return struct.pack('>BBBBBBB', b0, b1, b2, b3, b4, b5, b6)\n",
    "\n",
    "def clamp(val, mn, mx):\n",
    "    if val < mn:\n",
    "        return mn\n",
    "    if val > mx:\n",
    "        return mx\n",
    "    return val\n",
    "\n",
    "def encode(data):\n",
    "    speed = clamp(int(data['speed']), 0, 255)\n",
    "    course = clamp(int(data['course']), 0, 359) // 2\n",
    "    altitude = clamp(int(data['altitude']), 0, 1023) // 8\n",
    "    temperature = clamp(int(data['temperature'] * 2 + 0.5), -128, 127) + 128\n",
    "    status = 0\n",
    "    if data.get('battLow'): status |= 0x08\n",
    "    if data.get('gpsGood'): status |= 0x04\n",
    "    if data.get('ignition'): status |= 0x02\n",
    "    if data.get('pto'): status |= 0x01\n",
    "    ret = struct.pack('B', status)\n",
    "    ret += packll(data['latitude'], data['longitude'])\n",
    "    ret += struct.pack('BBBB', speed, course, altitude, temperature)\n",
    "    return binascii.hexlify(ret)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "def unpackll(ll):\n",
    "    b0, b1, b2, b3, b4, b5, b6 = map(int, ll)\n",
    "    latitude = (b0 << 20) | (b1 << 12) | (b2 << 4) | (b3 >> 4)\n",
    "    longitude = (b3 & 0x0f) << 24 | (b4 << 16) | (b5 << 8) | b6\n",
    "    latitude = (float(latitude) / 600000) - 180\n",
    "    longitude = (float(longitude) / 600000) - 180\n",
    "    return latitude, longitude\n",
    "\n",
    "def decode(payload):\n",
    "    data = {}\n",
    "    payload = binascii.unhexlify(payload)\n",
    "    data['latitude'], data['longitude'] = unpackll(payload[1:8])\n",
    "    data['speed'] = int(payload[8])\n",
    "    data['course'] = int(payload[9]) * 2\n",
    "    data['altitude'] = int(payload[10]) * 8\n",
    "    data['temperature'] = float(payload[11]) / 2 - 64\n",
    "    status = payload[0]\n",
    "    data['battLow'] = bool(status & 0x08)\n",
    "    data['gpsGood'] = bool(status & 0x04)\n",
    "    data['ignition'] = bool(status & 0x02) # Digital Input on TBSA\n",
    "    data['pto'] = bool(status & 0x01)\n",
    "    return data\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'0151736bccaa18b8201e0b98'\n",
      "{'latitude': -37.654300000000006, 'longitude': 174.1234, 'speed': 32, 'course': 60, 'altitude': 88, 'temperature': 12.0, 'battLow': False, 'gpsGood': False, 'ignition': False, 'pto': True}\n"
     ]
    }
   ],
   "source": [
    "data = {\n",
    "    'latitude': -37.6543,\n",
    "    'longitude': 174.1234,\n",
    "    'speed': 32,\n",
    "    'course': 60,\n",
    "    'altitude': 88,\n",
    "    'temperature': 12.2,\n",
    "    'pto': True\n",
    "}\n",
    "payload = encode(data)\n",
    "print(payload)\n",
    "dec = decode(payload)\n",
    "print(dec)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'latitude': -36.897115000000014, 'longitude': 174.77469000000002, 'speed': 12, 'course': 296, 'altitude': 224, 'temperature': 23.5, 'battLow': False, 'gpsGood': True, 'ignition': False, 'pto': False}\n"
     ]
    }
   ],
   "source": [
    "print(decode(b'0451e2563cb00f2e0c941caf'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'latitude': -36.897099999999995, 'longitude': 174.77464500000002, 'speed': 1, 'course': 166, 'altitude': 248, 'temperature': 22.5, 'battLow': False, 'gpsGood': True, 'ignition': False, 'pto': False}\n"
     ]
    }
   ],
   "source": [
    "print(decode(b'0451e256ccb00f1301531fad'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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