SAM7X256_14 Datasheet, PDF (503/662 Pages) ATMEL Corporation – ARM-based Flash MCU

the consumer mailbox must have a lower number than the Receive with Overwrite mailbox. The transfer command can
be triggered for all mailboxes at the same time by setting several MBx fields in the CAN_TCR register.
Figure 36-18. Consumer Handling
CAN BUS
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
MTCR
(CAN_MCRx)
Remote Frame
Message x
Remote Frame
Message y
(CAN_MDLx
CAN_MDHx)
Message x
Message y
36.7.4 CAN Controller Timing Modes
Using the free running 16-bit internal timer, the CAN controller can be set in one of the two following timing modes:
 Timestamping Mode: The value of the internal timer is captured at each Start Of Frame or each End Of Frame.
 Time Triggered Mode: The mailbox transfer operation is triggered when the internal timer reaches the mailbox
trigger.
Timestamping Mode is enabled by clearing the TTM bit in the CAN_MR register. Time Triggered Mode is enabled by
setting the TTM bit in the CAN_MR register.
36.7.4.1 Timestamping Mode
Each mailbox has its own timestamp value. Each time a message is sent or received by a mailbox, the 16-bit value
MTIMESTAMP of the CAN_TIMESTP register is transferred to the LSB bits of the CAN_MSRx register. The value read in
the CAN_MSRx register corresponds to the internal timer value at the Start Of Frame or the End Of Frame of the
message handled by the mailbox.
Figure 36-19. Mailbox Timestamp
Start of Frame
End of Frame
CAN BUS
CAN_TIM
TEOF
(CAN_MR)
TIMESTAMP
(CAN_TSTP)
MTIMESTAMP
(CAN_MSRx)
MTIMESTAMP
(CAN_MSRy)
Message 1
Timestamp 1
Timestamp 1
Message 2
Timestamp 2
Timestamp 2
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
503