AT572D940HF_14 Datasheet, PDF (682/745 Pages) ATMEL Corporation – High Performance MagicV VLIW DSP

After a remote frame has been received, the mailbox functions like a transmit mailbox. The mes-
sage with the highest priority is sent first. The transmitted message may be aborted by setting
the MACR bit in the CAN_MCR register. Please refer to the section “Transmission Handling” on
page 679.
Figure 33-17. Producer Handling
CAN BUS
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
MTCR
(CAN_MCRx)
Remote Frame
Message 1
Remote Frame
Reading CAN_MSRx
Remote Frame Message 2
(CAN_MDLx
CAN_MDHx)
Message 1
Message 2
33.7.3.3.1
Consumer Configuration
A mailbox is in Consumer Mode once the MOT field in the CAN_MMRx register has been config-
ured. Message ID and Message Acceptance masks must be set before Receive Mode is
enabled.
After Consumer Mode is enabled, the MRDY flag in the CAN_MSR register is automatically
cleared until the first transfer request command. The software application sends a remote frame
by setting the MTCR bit in the CAN_MCRx register or the MBx bit in the global CAN_TCR regis-
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.
682 AT572D940HF Preliminary
7010A–DSP–07/08