According to the AT90CAN64 documentation:
"This timer starts counting from 0x0000 when the CAN controller is enabled (ENFG bit)."
And this timer is used to stamp the CAN frames.
"The capture of the timer value is done in the MOb which receives or sends the frame. All managed
MOb are stamped, the stamping of a received (sent) frame occurs on RxOk (TXOK)."
In my code, after I received a few CAN frames, I disable the CAN interface, then to receive another few CAN frames, I enable it. So, I would expect the timer to be reset. But the time stamps of the frames appear to just increase, and eventually overrun.
Please, see the code attached. The subroutine is sending a single frame OBD command, and stores the response in OBD_BUFFER. It also sends flow control frame in case of multiframe OBD responses, according to ISO15765-2.