DESIGN OF A CUSTOM ASIC INCORPORATING CAN™ AND 1 ...

procedure, then the address claim process will result in addresses being assigned from zero to 24.
If a new higher priority node is added to the CAN bus at a later time, all of the existing 25
CAN nodes will be bumped off to a lower priority address resulting in a complete
reassignment of CAN node addresses. This problem can be avoided by reserving some
addresses at regular intervals. These addresses can be claimed by the CAN nodes only if they
are being bumped out of a valid address claimed status and cannot be claimed during the initial
configuration [40]. The reader is referred to [40] for a complete state machine diagram of the
address claim process.
The last proposed method to solve the issue of bridging message ID-based and address-
based protocols such as CAN and 1 – Wire® would require that the PIC® microcontroller and
CAN Controller used in the prototype system be CANopen® compliant. One of the biggest
challenges in developing the hardware for a CANopen® compliant node can be selecting the
right part, as some 20 chip manufacturers produce microcontrollers with CANopen® compliant
CAN interfaces.
CANopen® is a CAN - based higher layer application protocol conceived for process
control and automated manufacturing environments that, at present, is knowing widespread
diffusion all over the world and, in particular, in the European countries. CANopen® requires
that each device in the network be assigned a unique node address (Node – ID) before the normal
operations are started. To this extent, the CANopen® specifications provide a means to remotely
configure the addresses of the slave devices attached to the CAN bus. This technique,
however, requires that each device has to be connected separately to a configuration tool.
CANopen®, in fact, does not have a mechanism to identify, in an efficient and reliable way, the
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