CANopen and the need for time-stamping

Hello,
            Some CAN implementations have a built-in timer for time-stamping of messages. These timers also provide a time-out interrupt should transmission or reception of a mailbox does not occur in a pre-determined time. The eCAN module of in the 28xx MCUs from TI is an example. My question is this: Is the presence of a built-in timer absolutely essential for CANopen implementation? (Note that I am not referring to timers that are external to the CAN module, since all MCUs have one or more of “general-purpose” timers). I believe the answer is “no”, since I see in the websites of many 3rd parties who develop CANopen stacks a list of processors and I know not all of them have a built-in timer/counter as part of the CAN IP.



Hareesh Jana