Maxim-integrated MAXQ7667 Manual do Utilizador descarregar pdf (Página 148)

8.4.2 LIN Frame

he LIN protocol uses a single message frame to synchronize and address the nodes and to exchange data between them. The mas-

ter sets the transmission speed and sends the message header shown in Figure 8-2. The header starts with the sync/break sequence

followed by the sync field. The slave recognizes the sync/break and sets up to receive the sync field. Once the slave receives the sync

field, it adjusts its internal baud rate to match the master. The slave then examines the identifier field and acknowledges the message

f the identifier field is within the slave’s identifier range. The slave then sends data to the master.

8.4.3 LIN Peripheral

Figure 8-2 shows the dedicated LIN hardware. The MAXQ core interfaces with the LIN peripheral through the registers in Module 3.

The application software configures the LIN controller for master or slave operation and monitors the LIN interrupts for status. The appli-

cation software writes and reads the SBUF register for sending data over the LIN bus. The checksum and parity calculations are done

in hardware and require no software intervention.

The LIN control registers and bit descriptions are detailed in Module 3 of the MAXQ7667 register specification.

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MAXQ7667 User’s Guide

Figure 8-3. LIN Block Diagram

MAXQ

CORE

INTERRUPTS

SBUF

TRANSMIT REGISTER

BREAK/SYNC

GENERATOR

LIN PROTOCOL

STATE MACHINES

LIN CONTROL

REGISTERS

CHECKSUM

PARITY

Tx FIFO

FILTER/RECEIVE

ID BOUNDARY

BAUD-RATE

GENERATOR

Tx PIN

Rx PIN

Rx FIFO

Figure 8-2. LIN Frame Format

YNC/BREAK SYNC FIELD IDENTIFIER DATA

ESPONSEHEADER

DATA n

1 2 ... 143 144 145 146 147 148 149 150 151 152 153 ... 346 347

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Maxim-integrated MAXQ7667 Manual do Utilizador Página 148