fetch_data.py

   1 #!/usr/bin/env python3
   2 # Model Dreamlink WH1080
   3 #
   4
   5 import usb.core
   6 import time
   7 import struct
   8 import math
   9 import datetime
  10
  11 VENDOR = 0x1941
  12 PRODUCT = 0x8021
  13 #WIND_DIRS = ['N', 'NNE', 'NE', 'ENE', 'E', 'ESE', 'SE', 'SSE', 'S', 'SSW', 'SW', 'WSW', 'W', 'WNW', 'NW', 'NNW']
  14
  15
  16 def open_ws():
  17     '''
  18     Open a connection to the device, using the PRODUCT and VENDOR information
  19     @return reference to the device
  20     '''
  21     usb_device = usb.core.find(idVendor=VENDOR, idProduct=PRODUCT)
  22
  23     if usb_device is None:
  24         raise ValueError('Device not found')
  25
  26     usb_device.get_active_configuration()
  27
  28     # If we don't detach the kernel driver we get I/O errors
  29     if usb_device.is_kernel_driver_active(0):
  30         usb_device.detach_kernel_driver(0)
  31
  32     return usb_device
  33
  34
  35 def read_block(device, offset):
  36     '''
  37     Read a block of data from the specified device, starting at the given offset.
  38     @Inputs
  39     device
  40         - usb_device
  41     offset
  42         - int value
  43     @Return byte array
  44     '''
  45
  46     least_significant_bit = offset & 0xFF
  47     most_significant_bit = offset >> 8 & 0xFF
  48
  49     # Construct a binary message
  50     tbuf = struct.pack('BBBBBBBB',
  51                        0xA1,
  52                        most_significant_bit,
  53                        least_significant_bit,
  54                        32,
  55                        0xA1,
  56                        most_significant_bit,
  57                        least_significant_bit,
  58                        32)
  59
  60     timeout = 1000  # Milliseconds
  61     retval = device.ctrl_transfer(0x21,  # USB Requesttype
  62                                0x09,  # USB Request
  63                                0x200,  # Value
  64                                0,  # Index
  65                                tbuf,  # Message
  66                                timeout)
  67
  68     return device.read(0x81, 32, timeout)
  69
  70
  71 def main():
  72     dev = open_ws()
  73     dev.set_configuration()
  74
  75
  76     ########### Read data
  77     # Get the first 32 Bytes of the fixed
  78     fixed_block = read_block(dev, 0)
  79
  80     # Check that we have good data
  81     if (fixed_block[0] != 0x55):
  82         raise ValueError('Bad data returned')
  83
  84     # Bytes 31 and 32 when combined create an unsigned short int that tells us where to find the weather data we want
  85     curpos = struct.unpack('H', fixed_block[30:32])[0]
  86     current_block = read_block(dev, curpos)
  87
  88     # Indoor information
  89     indoor_humidity = current_block[1]
  90     tlsb = current_block[2]
  91     tmsb = current_block[3] & 0x7f
  92     tsign = current_block[3] >> 7
  93     indoor_temperature = (tmsb * 256 + tlsb) * 0.1
  94     # Check if temperature is less than zero
  95     if tsign:
  96         indoor_temperature *= -1
  97
  98     # Outdoor information
  99     outdoor_humidity = current_block[4]
 100     tlsb = current_block[5]
 101     tmsb = current_block[6] & 0x7f
 102     tsign = current_block[6] >> 7
 103     outdoor_temperature = (tmsb * 256 + tlsb) * 0.1
 104     # Check if temperature is less than zero
 105     if tsign:
 106         outdoor_temperature *= -1
 107
 108     # Bytes 8 and 9 when combined create an unsigned short int that we multiply by 0.1 to find the absolute pressure
 109     abs_pressure = struct.unpack('H', current_block[7:9])[0]*0.1
 110
 111     wind = current_block[9]
 112     gust = current_block[10]
 113     wind_extra = current_block[11]
 114     wind_dir = current_block[12]
 115
 116     # Bytes 14 and 15  when combined create an unsigned short int
 117     # that we multiply by 0.3 to find the total rain
 118     # I'm not confident that this is correct. Neither abs_pressure nor
 119     # total_rain are returning sane values. In fact total_rain has
 120     # stayed static despite rainfall
 121     # Looks like I fixed it. They used fixed_block instead of current_block
 122     total_rain = struct.unpack('H', current_block[13:15])[0]*0.3
 123
 124     # Calculate wind speeds
 125     wind_speed = (wind + ((wind_extra & 0x0F) << 8)) * 0.38  # Was 0.1
 126     gust_speed = (gust + ((wind_extra & 0xF0) << 4)) * 0.38  # Was 0.1
 127
 128
 129     ############### print data
 130     print('{')
 131     print('"indoor_humidity": "%i",' %indoor_humidity)
 132     print('"indoor_temperature": "%2.1f",' %indoor_temperature)
 133     print('"outdoor_humidity": "%i",' %outdoor_humidity)
 134     print('"outdoor_temperature": "%2.1f",' %outdoor_temperature)
 135     print('"abs_pressure": "%4.1f",' %abs_pressure)
 136     print('"total_rain": "%3.1f",' %total_rain)
 137     print('"wind_speed": "%2.1f",' %wind_speed)
 138     print('"gust_speed": "%2.1f",' %gust_speed)
 139     if wind_dir != 128:
 140         print('"wind_dir_deg": "%s",' %(wind_dir*22.5))
 141 #        print('"wind_dir": "%s",' %WIND_DIRS[wind_dir])
 142     print('"TS": "%s"' %(datetime.datetime.utcnow().isoformat()))
 143     print('}')
 144
 145
 146 if __name__ == "__main__":
 147     main()