further info on canbus:
-----------------------


Volvo uses extended identifiers:
-------------------------------

CAN frames follow a defined format: all standard frames have an 11-bit
identifier and up to 8 bytes of data. Extended frames allow 29 bit identifiers,
but only the same 8 bytes of data. CAN frames also include checksums, and most
CAN implementations in microcontrollers will automatically insert / verify
checksums in hardware. 


.. image:: ../images/can_signalling.png

.. image:: ../images/can_frame.png

.. image:: ../images/filter_banks.png