mdb/backend: delay device open, adjust serial interface path

mdb/backend.py

@@ -83,15 +83,8 @@ class RaspiBackend(Backend):
 # Backend device based on STM32F1 MDB-USB adapter (to be actually designed...)
 #
 class SerialBackend(Backend):
-    def __init__(self, device='/dev/ttyACM0'):
-        import serial
-        self.ser = serial.Serial(device)
-
-        # FIXME clear buffer
-        self.ser.timeout = 0.2
-        while self.ser.read(1):
-            pass
-        self.ser.timeout = None
+    def __init__(self, device='/dev/serial/by-id/usb-vuko@hackerspace.pl_flowMeter_00001-if00'):
+        self.device = device
 
     def read(self):
         buf = b''
@@ -107,3 +100,13 @@ class SerialBackend(Backend):
     def write(self, data):
         self.ser.write(data)
         self.ser.flush()
+
+    def open(self):
+        import serial
+        self.ser = serial.Serial(self.device)
+
+        # FIXME clear buffer
+        self.ser.timeout = 0.2
+        while self.ser.read(1):
+            pass
+        self.ser.timeout = None