Specifications

Overview of the CAN Network
10-4
Figure 10–1. CAN Data Frame
Bit length 1 12 or 32 6 0–8 bytes 16 2 7
Start bit Control bits Data field CRC bits
Acknowledge
End
Arbitration field which contains:
- 11-bit identifier + RTR bit for standard frame format
- 29-bit identifier + SRR bit + IDE bit + RTR bit for extended frame format
Where: RTR = Remote Transmission Request
SRR = Substitute Remote Request
IDE = Identifier Extension
Note: Unless otherwise noted, numbers are amount of bits in field.
10.2.2 CAN Controller Architecture
Figure 10–2 shows the basic architecture of the CAN controller.
Figure 10–2. TMS320x240x CAN Module Block Diagram
CAN module
Control logic
CPU interface/
Memory management unit
CAN
Core
Control/Status registers
Interrupt logic
control
bus
Temporary receive buffer
Acceptance filter
transmit buffer
mailbox 0
mailbox 1
mailbox 2
mailbox 3
mailbox 4
mailbox 5
R
R
T/R
T/R
T
T
RAM 48x16
matched
data ID
CPU
’240x
CAN
Transceiver
Chip
CANTXCANRX
CAN Bus
ID