Added pycrc based checksum calculation to the CanMessage class.

CANLibrary/CanMessage.py

@@ -9,6 +9,8 @@ Created on 06.07.2012
 import array
 import sys
 
+from pycrc import Crc
+
 class CanMessage(object):
     
     '''
@@ -114,3 +116,18 @@ class CanMessage(object):
                 if tgtBitNo >= 8:
                     tgtBitNo = 0
                     tgtByteNo += 1
+    
+    '''
+    Calculate the CRC checksum over the whole message.
+    This works for the parameters used by VW, as a 0x00 byte somewhere in the message does not provide to the checksum.
+    
+    If this is true for all checksums is not certain! Has been tested for mMotor_5 and mMotor_6 only!
+    '''
+    def calculateCRC(self):
+        crc = Crc(width=8, poly=0x01, reflect_in = False, reflect_out = False, xor_in = 0xff, xor_out = 0xff)
+        self.composeData()
+        data = self.Data.tostring()
+        my_crc = crc.bit_by_bit_fast(data)
+        #print ("%x" % my_crc)
+        return my_crc
+