SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 1230

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

Figure 40-18. Consumer Handling
40.8.4
40.8.4.1
1230
1230
(CAN_MCRx)
(CAN_MSRx)
(CAN_MSRx)
CAN_MDHx)
(CAN_MDLx
CAN BUS
MRDY
MTCR
MMI
SAM3X/A
SAM3X/A
CAN Controller Timing Modes
Timestamping Mode
ter. The application is notified of the answer by the MRDY flag set in the CAN_MSRx register.
The application can read the data contents in the CAN_MDHx and CAN_MDLx registers. An
interrupt is pending for the mailbox while the MRDY flag is set. This interrupt can be masked
according to the mailbox flag in the CAN_IMR global register.
The MRTR bit in the CAN_MCRx register has no effect. This field is used only when using
Transmit Mode.
After a remote frame has been sent, the consumer mailbox functions as a reception mailbox.
The first message received is stored in the mailbox data registers. If other messages intended
for this mailbox have been sent while the MRDY flag is set in the CAN_MSRx register, they will
be lost. The application is notified by reading the MMI field in the CAN_MSRx register. The read
operation automatically clears the MMI flag.
If several messages are answered by the Producer, the CAN controller may have one mailbox in
consumer configuration, zero or several mailboxes in Receive Mode and one mailbox in Receive
with Overwrite Mode. In this case, 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.
Using the free running 16-bit internal timer, the CAN controller can be set in one of the two fol-
lowing timing modes:
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.
Each mailbox has its own timestamp value. Each time a message is sent or received by a mail-
box, 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 inter-
nal timer value at the Start Of Frame or the End Of Frame of the message handled by the
mailbox.
Remote Frame
• Timestamping Mode: The value of the internal timer is captured at each Start Of Frame or
• Time Triggered Mode: The mailbox transfer operation is triggered when the internal timer
each End Of Frame.
reaches the mailbox trigger.
Message x
Message x
Remote Frame
Message y
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Message y