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CHAPTER 19 FCAN CONTROLLER (V850/SC3)
User’s Manual U15109EJ3V0UD
630
19.7 Time Stamp Function
Caution
In the V850/SC3, the time stamp function by SOF detection during message
transmission/reception cannot be used.
Only the time stamp function by EOF detection during message reception can be used for the
V850/SC3. However, only the value captured by the M_TIME register is valid when the TSM bit of
the CGST register is set to 1 and the TMR bit of the CnCTRL register is set to 1.
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 CANx control register (CxCTRL) to set the desired time stamp function (x = 1, 2). When the TMRT bit is 0, the
time stamp counter value is captured after the SOF is sent via the CAN bus (see
Figure 19-5
) and when the TMR bit
is 1, the time stamp counter value is captured after the EOF is sent via the CAN bus (a valid message is confirmed)
(see
Figure 19-6
).
Figure 19-5. Time Stamp Function Setting for Message Reception (When CxCTRL Register’s TMR Bit = 0)
Message
ACK field
EOF
SOF
<2>
<1>
Time stamp
counter
Temporary
buffer
M_TIMEn
CAN message buffer n
<Explanation>
<1> The time stamp counter value is captured when the SOF is sent via 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 sent via the CAN bus.
Remark
n = 00 to 31
x = 1, 2