Rainbow Electronics ATmega64C1 - Manual (Page 173)

173
7647A–AVR–02/08
ATmega32/64/M1/C1
16.3 CAN Controller
The CAN controller implemented into ATmega32/64/M1/C1 offers V2.0B Active.
This full-CAN controller provides the whole hardware for convenient acceptance filtering and
message management. For each message to be transmitted or received this module contains
one so called message object in which all information regarding the message (e.g. identifier,
data bytes etc.) are stored.
During the initialization of the peripheral, the application defines which messages are to be sent
and which are to be received. Only if the CAN controller receives a message whose identifier
matches with one of the identifiers of the programmed (receive-) message objects the message
is stored and the application is informed by interrupt. Another advantage is that incoming remote
frames can be answered automatically by the full-CAN controller with the corresponding data
frame. In this way, the CPU load is strongly reduced compared to a basic-CAN solution.
Using full-CAN controller, high baudrates and high bus loads with many messages can be
handled.
Figure 16-5. CAN Controller Structure
CAN Channel
Gen. Control
Gen. Status
Enable MOb
Interrupt
Bit Timing
Line Error
CAN Timer
LCC
MAC
PLS
Internal
TxCAN
Internal
RxCAN
M a i l b o x
Message Objets
MOb0
MOb1
MOb2
MOb i
Control
Status
IDtag+IDmask
Time Stamp
Control
Status
IDtag+IDmask
Time Stamp
Control
Status
IDtag+IDmask
Time Stamp
Control
Status
IDtag+IDmask
Time Stamp
Buffer MOb0
Buffer MOb1
Buffer MOb2
Buffer MOb i
CAN Data Buffers
Size=120 Bytes
Low priority
High priority
MOb
Scanning