Fixed bug issue 4. Updated README.

README.md

@@ -202,8 +202,14 @@ Let us know how it went! If you want contribute, you can do so by posting issues
 
 # Release notes
 
+Release dated 14-Jan-2019
+
+* [bug] Fixed issue ([#4][i4])
+
 Release dated 14-Dec-2018
 
 * Added SAMPLE-PERIOD as an input argument.
 
-Initial release 12-Dec-2018
+Initial release 12-Dec-2018
+
+[i4]: https://github.com/Airthings/waveplus-reader/issues/4

read_waveplus.py

@@ -106,32 +106,42 @@ class WavePlus():
     def __init__(self, SerialNumber):
         self.periph        = None
         self.curr_val_char = None
+        self.MacAddr       = None
+        self.SN            = SerialNumber
         self.uuid          = UUID("b42e2a68-ade7-11e4-89d3-123b93f75cba")
 
     def connect(self):
-        scanner     = Scanner().withDelegate(DefaultDelegate())
-        deviceFound = False
-        searchCount = 0
-        while deviceFound is False and searchCount < 50:
-            devices      = scanner.scan(0.1) # 0.1 seconds scan period
-            searchCount += 1
-            for dev in devices:
-                ManuData = dev.getValueText(255)
-                SN = parseSerialNumber(ManuData)
-                if (SN == SerialNumber):
-                    MacAddr = dev.addr
-                    deviceFound  = True # exits the while loop on next conditional check
-                    break # exit for loop
+        # Auto-discover device on first connection
+        if (self.MacAddr is None):
+            scanner     = Scanner().withDelegate(DefaultDelegate())
+            searchCount = 0
+            while self.MacAddr is None and searchCount < 50:
+                devices      = scanner.scan(0.1) # 0.1 seconds scan period
+                searchCount += 1
+                for dev in devices:
+                    ManuData = dev.getValueText(255)
+                    SN = parseSerialNumber(ManuData)
+                    if (SN == self.SN):
+                        self.MacAddr = dev.addr # exits the while loop on next conditional check
+                        break # exit for loop
+
+            if (self.MacAddr is None):
+                print "ERROR: Could not find device."
+                print "GUIDE: (1) Please verify the serial number."
+                print "       (2) Ensure that the device is advertising."
+                print "       (3) Retry connection."
+                sys.exit(1)
 
-        if (deviceFound is not True):
-            print "ERROR: Could not find device."
-            print "GUIDE: (1) Please verify the serial number. (2) Ensure that the device is advertising. (3) Retry connection."
-            sys.exit(1)
-        else:
-            self.periph = Peripheral(MacAddr)
+        # Connect to device
+        if (self.periph is None):
+            self.periph = Peripheral(self.MacAddr)
+        if (self.curr_val_char is None):
             self.curr_val_char = self.periph.getCharacteristics(uuid=self.uuid)[0]
 
     def read(self):
+        if (self.curr_val_char is None):
+            print "ERROR: Devices are not connected."
+            sys.exit(1)            
         rawdata = self.curr_val_char.read()
         rawdata = struct.unpack('BBBBHHHHHHHH', rawdata)
         sensors = Sensors()
@@ -141,6 +151,8 @@ def read(self):
     def disconnect(self):
         if self.periph is not None:
             self.periph.disconnect()
+            self.periph = None
+            self.curr_val_char = None
 
 # ===================================
 # Class Sensor and sensor definitions
@@ -189,9 +201,8 @@ def getUnit(self, sensor_index):
         return self.sensor_units[sensor_index]
 
 try:
-    #---- Connect to device ----#
+    #---- Initialize ----#
     waveplus = WavePlus(SerialNumber)
-    waveplus.connect()
 
     if (Mode=='terminal'):
         print "\nPress ctrl+C to exit program\n"
@@ -207,6 +218,8 @@ def getUnit(self, sensor_index):
 
     while True:
 
+        waveplus.connect()
+
         # read values
         sensors = waveplus.read()
 
@@ -226,7 +239,9 @@ def getUnit(self, sensor_index):
             print tableprint.row(data, width=12)
         elif (Mode=='pipe'):
             print data
-
+
+        waveplus.disconnect()
+
         time.sleep(SamplePeriod)
 
 finally: