--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wh1080.py	Sat Feb 13 18:19:42 2010 +1030
@@ -0,0 +1,150 @@
+#!/usr/bin/env python
+
+import struct
+import usb
+
+WH1080_VENDOR = 0x1941
+WH1080_DEVICE = 0x8021
+
+WH1080_TIMEOUT = 100
+
+WH1080_RECORD_SIZE = 32
+WH1080_PAGE_SIZE = 32
+WH1080_BASE = 0x100
+
+WH1080_PAGE0_MAGIC1A = 0xffffffffffffaa55
+WH1080_PAGE0_MAGIC1B = 0xffffffffffaaaa55
+WH1080_PAGE0_MAGIC2  = 0xffffffffffffffff
+
+WH1080_WIND_DIRECTIONS = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE",
+                          "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"]
+
+def apparent_temp(Ta, rh, ws, Q = None):
+    """Compute apparent temperature. Obtained from the Australian BOM at http://www.bom.gov.au/info/thermal_stress/
+Ta = dry bulb temperature (Celcius)
+rh = relative humidity (percentage)
+ws = Wind speed (m/s)
+Q = net radiation absorbed by body (W/m2) (optional)"""
+    e = rh / 100 * 6.105 * exp(17.27 * Ta / (237.7 + Ta))
+
+    if Q == None:
+        return(Ta + 0.33 * e - 0.70 * ws - 4.00)
+    else:
+        return(Ta + 0.33 * e - 0.70 * ws + 0.70 * Q/(ws + 10) - 4.25)
+
+def list2uintN(l, size):
+    res = 0
+    for i in xrange(size):
+        res += l[i] << 8 * i
+    return res
+
+class WH1080(object):
+    def __init__(self):
+
+        busses = usb.busses()
+
+        #
+        # Search for the device we want
+        #
+        self.handle = None
+        for bus in busses:
+            for dev in bus.devices:
+                #print "Looking at 0x%04x 0x%04x" % (dev.idVendor, dev.idProduct)
+                if dev.idVendor == WH1080_VENDOR and dev.idProduct == WH1080_DEVICE:
+                    # Open the device and claim the USB interface that supports the spec
+                    self.handle = dev.open()
+                    self.dev = dev
+                    break
+
+        if self.handle == None:
+            raise "Could not find a suitable USB device"
+        self.handle.claimInterface(0)
+
+    def get_current_record(self):
+        page0 = Page0(self.read_page(0))
+        return(page0.current_record)
+
+    def read_current_record(self):
+        return self.read_record(self.get_current_record())
+
+    def read_record(self, record):
+        """Read the nominated record from the device"""
+
+        # Calculate offset for this record
+        ofs = (record * WH1080_PAGE_SIZE) + WH1080_BASE
+        # 32 bytes covers 2 records.
+        # We don't want to read past the end of memory so we start at
+        # the even page then pick what we need.
+        ofs &= ~WH1080_RECORD_SIZE
+
+        data = self.read_page(ofs)
+        #print "Reading record %d => 0x%04x" % (record, ofs)
+        if record % 2:
+            data = data[0:16]
+        else:
+            data = data[16:32]
+            
+        return Reading(data)
+
+    def read_page(self, ofs):
+        """Read a page from the device at ofs
+Due to apparent hardware bugs / race conditions we read a few times until we have 2 identical reads"""
+        for t in xrange(10):
+            pageA = self._read_page(ofs)
+            pageB = self._read_page(ofs)
+            if pageA == pageB:
+                break
+        else:
+            raise IOError("Could not read page cleanly")
+
+        return pageA
+            
+    def _read_page(self, ofs):
+        """Read a page from from the device at ofs (no retries)"""
+        msb = (ofs >> 8) & 0xff
+        lsb = ofs & 0xff
+
+        req = [0xa1, msb, lsb, 0x20] * 2
+        if self.handle.controlMsg(usb.TYPE_CLASS | usb.RECIP_INTERFACE, 0x9, req, value = 0x200, timeout = WH1080_TIMEOUT) != 8:
+            raise IOError("Unable to send control message")
+        
+        data = self.handle.interruptRead(usb.ENDPOINT_IN | usb.RECIP_INTERFACE, WH1080_PAGE_SIZE, WH1080_TIMEOUT)
+        if len(data) != WH1080_PAGE_SIZE:
+            raise IOError("Unable to read from endpoint expected %d bytes got %d" % 
+                          (WH1080_PAGE_SIZE, len(data)))
+            
+        data = map(chr, data)
+        return reduce(lambda a, b: a + b, data)
+
+class Page0(object):
+    """Decode page 0, which contains a pointer to the current page"""
+    def __init__(self, data):
+        (magic1, magic2, current_offset) = struct.unpack('< Q Q 14x H', data)
+        if (magic1 != WH1080_PAGE0_MAGIC1A and magic1 != WH1080_PAGE0_MAGIC1B) or magic2 != WH1080_PAGE0_MAGIC2:
+            raise ValueError("page0 magic not valid")
+
+        self.current_record = (current_offset - WH1080_BASE) / WH1080_PAGE_SIZE
+        #print "Offset 0x%04x => %d" % (current_offset, self.current_record)
+
+class Reading(object):
+    def __init__(self, data):
+        (self.last_save_mins, self.inside_humidity, self.inside_temp, 
+         self.outside_humidity, self.outside_temp, self.pressure,
+         self.wind_speed, self.wind_gust, foo, self.wind_direction,
+         self.rain, bar) = struct.unpack('< B B h B h H B B B B H B', data)
+
+        #print "foo = 0x%02x, bar = 0x%02x" % (foo, bar)
+        self.inside_temp /= 10.0
+        self.outside_temp /= 10.0
+        self.wind_speed /= 10.0
+        self.pressure /= 10.0
+        if self.wind_direction == 0x80 or self.wind_direction == 0xff:
+            self.wind_direction = None
+        else:
+            self.wind_direction = WH1080_WIND_DIRECTIONS[self.wind_direction]
+        
+    def __str__(self):
+        return "%2d %4.1f %3d %4.1f %3d %6.1f %5.1f %5.1f %s %4.1f" % (
+            self.last_save_mins, self.inside_temp, self.inside_humidity, self.outside_temp,
+            self.outside_humidity, self.pressure, self.wind_speed, self.wind_gust,
+            self.wind_direction, self.rain)