Add support for filtering by usb serial number (#22)

radiacode/radiacode.py

@@ -18,12 +18,17 @@ def spectrum_channel_to_energy(channel_number: int, a0: float, a1: float, a2: fl
 class RadiaCode:
     _connection: Union[Bluetooth, Usb]
 
-    def __init__(self, bluetooth_mac: Optional[str] = None, ignore_firmware_compatibility_check: bool = False):
+    def __init__(
+        self,
+        bluetooth_mac: Optional[str] = None,
+        serial_number: Optional[str] = None,
+        ignore_firmware_compatibility_check: bool = False,
+    ):
         self._seq = 0
         if bluetooth_mac is not None:
             self._connection = Bluetooth(bluetooth_mac)
         else:
-            self._connection = Usb()
+            self._connection = Usb(serial_number=serial_number)
 
         # init
         self.execute(b'\x07\x00', b'\x01\xff\x12\xff')

radiacode/transports/usb.py

@@ -18,8 +18,16 @@ def __init__(self, message=None):
 
 
 class Usb:
-    def __init__(self, timeout_ms=3000):
-        self._device = usb.core.find(idVendor=0x483, idProduct=0xF123)
+    def __init__(self, serial_number=None, timeout_ms=3000):
+        _vid = 0x0483
+        _pid = 0xF123
+
+        if serial_number:
+            self._device = usb.core.find(idVendor=_vid, idProduct=_pid, serial_number=serial_number)
+        else:
+            # usb.core.find(..., serial_number=None) will attempt to match against a value of None,
+            # rather than ignoring it as a match condition.
+            self._device = usb.core.find(idVendor=_vid, idProduct=_pid)
         self._timeout_ms = timeout_ms
         if self._device is None:
             raise DeviceNotFound