CONTROLLER AREA NETWORK (bxCAN)
Tx Mailboxes
CONTROLLER AREA NETWORK (Cont’d)
CAN 2.0B Active Core
The bxCAN module handles the transmission and
the reception of CAN messages fully autonomous-
ly. Standard identifiers (11-bit) and extended iden-
tifiers (29-bit) are fully supported by hardware.
Three transmit mailboxes are provided to the soft-
ware for setting up messages. The transmission
Scheduler decides which mailbox has to be trans-
mitted first.
Control, Status and Configuration Registers
The application uses these registers to:
– Configure CAN parameters, e.g.baud rate
– Request transmissions
Acceptance Filters
The bxCAN provides eight scalable/configurable
identifier filter banks for selecting the incoming
messages the software needs and discarding the
others.
– Handle receptions
Receive FIFO
– Manage interrupts
Two receive FIFOs are used by hardware to store
the incoming messages. Three complete messag-
es can be stored in each FIFO. The FIFOs are
managed completely by hardware.
– Get diagnostic information
Figure 143. CAN Block Diagram
Tx Mailboxes
Receive FIFO 0
Receive FIFO 1
Master Control
Mailbox 2
2
2
1
1
Master Status
Mailbox 0
Mailbox 0
Transmit Control
Mailbox 1
Transmit Status
Transmit Priority
Receive FIFO
Mailbox 0
Interrupt Enable
Page Select
Acceptance Filters
Error Status
7
6
5
4
Error Int. Enable
3
2
1
Transmission
0
Filter
Tx Error Counter
Scheduler
Rx Error Counter
Diagnostic
Bit Timing
CAN 2.0B Active Core
Filter Mode
Filter Config.
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STMICROELECTRONICS [ ST ]
