Time Stamp Function - NEC UPD703116 User Manual

11.4 Time Stamp Function

The FCAN controller supports a time stamp function. This function is needed to build a global time system.
The time stamp function is implemented using a 16-bit free-running time stamp counter.
Two types of time stamp function can be selected for message reception in the FCAN controller. Use bit 3 (TMR)
of the CAN1 control register (C1CTRL) to set the desired time stamp function. When the TMR bit is 0, the time stamp
counter value is captured after the SOF is detected on the CAN bus (see Figure 11-2) and when the TMR bit is 1, the
time stamp counter value is captured after the EOF is detected on the CAN bus (a valid message is confirmed) (see
Figure 11-3).
Figure 11-2. Time Stamp Function Setting for Message Reception (When C1CTRL Register's TMR Bit = 0)
SOF
<1>
Time stamp
counter
<Explanation>
<1> The time stamp counter value is captured to the temporary buffer when the SOF is detected on the CAN
bus.
<2> A message is stored in CAN message buffer n and the value in the temporary buffer is copied to the
M_TIMEn register in CAN message buffer n when the EOF is detected on the CAN bus.
Remark n = 00 to 31
CHAPTER 11 FCAN CONTROLLER
ACK field
Message
Temporary
buffer
User's Manual U14492EJ5V0UD
EOF
CAN message buffer n
<2>
M_TIMEn
517