Rainbow Electronics AT91CAP9S250A - Manual (Page 681)

681
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
39. Controller Area Network (CAN)
39.1 Description
The CAN controller provides all the features required to implement the serial communication
protocol CAN defined by Robert Bosch GmbH, the CAN specification as referred to by
ISO/11898A (2.0 Part A and 2.0 Part B) for high speeds and ISO/11519-2 for low speeds. The
CAN Controller is able to handle all types of frames (Data, Remote, Error and Overload) and
achieves a bitrate of 1 Mbit/sec.
CAN controller accesses are made through configuration registers. 16 independent message
objects (mailboxes) are implemented.
Any mailbox can be programmed as a reception buffer block (even non-consecutive buffers).
For the reception of defined messages, one or several message objects can be masked with-
out participating in the buffer feature. An interrupt is generated when the buffer is full.
According to the mailbox configuration, the first message received can be locked in the CAN
controller registers until the application acknowledges it, or this message can be discarded by
new received messages.
Any mailbox can be programmed for transmission. Several transmission mailboxes can be
enabled in the same time. A priority can be defined for each mailbox independently.
An internal 16-bit timer is used to stamp each received and sent message. This timer starts
counting as soon as the CAN controller is enabled. This counter can be reset by the applica-
tion or automatically after a reception in the last mailbox in Time Triggered Mode.
The CAN controller offers optimized features to support the Time Triggered Communication
(TTC) protocol.