MikroElektronika PIC Microcontrollers PIC18 Manuel d'utilisateur télécharger pdf (Page 6)

circuit and a capacitor are used at either end of the bus. This method increases the EMC

performance of the bus (Figure 9.5(c)).

Many network protocols are described using the seven-layer Open Systems

Interconnection (OSI) model. The CAN protocol includes the data link layer, and

the physical layer of the OSI reference model (see Figure 9.6). The data link layer

(DLL) consists of the Logical Link Control (LLC) and Medium Access Control

(MAC). LLC manages the overload notification, acceptance filtering, and recovery

management. MAC manages the data encapsulation, frame coding, error detection,

and serialization/deserialization of the data. The physical layer consists of the

physical signaling layer (PSL), physical medium attachment (PMA), and the

medium dependent interface (MDI). PSL manages the bit encoding/decoding and

bit timing. PMA manages the driver/receiver characteristics, and MDI is the

connections and wires.

120 ohm

Standard termination

(a)

60 ohm

Split termination

(b)

VDD

60 ohm

Biased split termination

60 ohm

(c)

Figure 9.5: Bus termination methods

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MikroElektronika PIC Microcontrollers PIC18 Manuel d'utilisateur Page 6