BAT32G1x9 user manual | Chapter 22 CAN control
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22.2 CAN protocol
CAN (Controller Area Network) is a high-speed multiplexed communication protocol for real-time
communication in automotive applications (Class C). CAN is regulated by ISO 11898. For more
information, see the ISO 11898 specification.
The CAN specification is usually divided into two layers: the physical layer and the data link layer,
which in turn contains logical links and media access control. The composition of these layers is shown in
the following figure:
Figure 22-2. The composition of layers
高
low
1: CAN controller specification
22.2.1
Frame format
(1) Standard frame format
- The standard frame format uses 11-bit identifiers, which means it can handle 2048 signals.
(2) Extend the format frame
- Extended format frames use 29-bit (11-bit + 18-bit) identifiers, which can handle 2048x218 signals.
-
Sets the extended format frame when the "implicit level" is set for the SRR and IDE bits in the arbitration field
(CMOS level equals "1").
Data links
Layer
1
·
Logical Link Control (LLC
).
·
Acceptance filtering
·
Overload notification
·
Recovery management
·
Media Access Control (MAC
).
·
Data packets/unpacking
·
Frame encoding (fill/depopulate)
·
Media access management
·
Error detection, calibration
·
Error reporting
·
Response
·
Serialized/non-serialized
Physical layer
Specification of signal levels and bit
descriptions