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Many network protocols are described using the seven
layer Open System Interconnection (OSI) model, as
shown in Figure 1. The Controller Area Network (CAN)
protocol defines the Data Link Layer and part of the
Physical Layer in the OSI model. The remaining physi-
cal layer (and all of the higher layers) are not defined by
the CAN specification. These other layers can either be
defined by the system designer, or they can be imple-
mented using existing non-proprietary Higher Layer
Protocols (HLPs) and physical layers.
The Data Link Layer is defined by the CAN specifica-
tion. The Logical Link Control (LLC) manages the over-
load control and notification, message filtering and
recovery management functions. The Medium Access
Control (MAC) performs the data encapsulation/decap-
sulation, error detection and control, bit stuffing/de-
stuffing and the serialization and deserialization
functions.
M AN228
A CAN Physical Layer Discussion
The Physical Medium Attachment (PMA) and Medium
Author: Pat Richards
Dependent Interface (MDI) are the two parts of the
Microchip Technology Inc.
physical layer which are not defined by CAN. The
Physical Signaling (PS) portion of the physical layer is
INTRODUCTION defined by the CAN specification. Th

关键词： CAN   物理层