Add log_event method and channel to ASCWriter.

Author: christiansandberg

can/CAN.py

@@ -230,24 +230,33 @@ class ASCWriter(Listener):
     """Logs CAN data to an ASCII log file (.asc)"""
 
     LOG_STRING = "{time: 9.4f} {channel}  {id:<15} Rx   d {dlc} {data}\n"
+    EVENT_STRING = "{time: 9.4f} {message}\n"
 
-    def __init__(self, filename):
+    def __init__(self, filename, channel=1):
         now = datetime.now().strftime("%a %b %m %I:%M:%S %p %Y")
+        self.channel = channel
         self.started = time.time()
         self.log_file = open(filename, "w")
         self.log_file.write("date %s\n" % now)
         self.log_file.write("base hex  timestamps absolute\n")
         self.log_file.write("internal events logged\n")
         self.log_file.write("Begin Triggerblock %s\n" % now)
-        self.log_file.write("   0.0000 Start of measurement\n")
+        self.log_event("Start of measurement")
 
     def stop(self):
         """Stops logging and closes the file."""
-        if self.log_file:
+        if self.log_file is not None:
             self.log_file.write("End TriggerBlock\n")
             self.log_file.close()
             self.log_file = None
 
+    def log_event(self, message):
+        """Add an arbitrary message to the log file."""
+        timestamp = time.time() - self.started
+        line = self.EVENT_STRING.format(time=timestamp, message=message)
+        if self.log_file is not None:
+            self.log_file.write(line)
+
     def on_message_received(self, msg):
         data = ["{:02X}".format(byte) for byte in msg.data]
         arb_id = "{:X}".format(msg.arbitration_id)
@@ -258,9 +267,9 @@ def on_message_received(self, msg):
             timestamp -= self.started
 
         line = self.LOG_STRING.format(time=timestamp,
-                                      channel=1,
+                                      channel=self.channel,
                                       id=arb_id,
                                       dlc=msg.dlc,
                                       data=" ".join(data))
-        if self.log_file:
+        if self.log_file is not None:
             self.log_file.write(line)

test/listener_test.py

@@ -66,7 +66,8 @@ def testSQLWriterReceives(self):
         assert msg[1] == 0xDADADA
 
     def testAscListener(self):
-        a_listener = can.ASCWriter("test.asc")
+        a_listener = can.ASCWriter("test.asc", channel=2)
+        a_listener.log_event("This is some comment")
         msg = can.Message(extended_id=True,
                           timestamp=a_listener.started + 0.5,
                           arbitration_id=0xabcdef,