at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 679

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

Figure 37-16. Producer / Consumer Model
6249D–ATARM–20-Dec-07
Producer Configuration
In Pull Mode, a consumer transmits a remote frame to the producer. When the producer
receives a remote frame, it sends the answer accepted by one or many consumers. Using trans-
mit and receive mailboxes, a consumer must dedicate two mailboxes, one in Transmit Mode to
send remote frames, and at least one in Receive Mode to capture the producer’s answer. The
same structure is applicable to a producer: one reception mailbox is required to get the remote
frame and one transmit mailbox to answer.
Mailboxes can be configured in Producer or Consumer Mode. A lonely mailbox can handle the
remote frame and the answer. With 16 mailboxes, the CAN controller can handle 16 indepen-
dent producers/consumers.
A mailbox is in Producer 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 Producer Mode is enabled, the MRDY flag in the CAN_MSR register is automatically set
until the first transfer command. The software application prepares data to be sent by writing to
the CAN_MDHx and the CAN_MDLx registers, then by setting the MTCR bit in the CAN_MCRx
register. Data is sent after the reception of a remote frame as soon as it wins the bus arbitration.
The MRDY flag remains at zero as long as the message has not been sent or aborted. No
access to the mailbox data register can be done while MRDY flag is cleared. 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.
If a remote frame is received while no data are ready to be sent (signal MRDY set in the
CAN_MSRx register), then the MMI signal is set in the CAN_MSRx register. This bit is cleared
by reading the CAN_MSRx register.
The MRTR field in the CAN_MSRx register has no meaning. This field is used only when using
Receive and Receive with Overwrite modes.
Indications
Request
Response
Producer
Producer
PUSH MODEL
PULL MODEL
CAN Remote Frame
CAN Data Frame
CAN Data Frame
AT91SAM9263 Preliminary
Consumer
Confirmation(s)
Consumer
Request(s)
Indication(s)
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