Maxim-integrated MAXQ7667 Bedienungsanleitung PDF herunterladen (Seite 149)

8.4.4 LIN Master

he MAXQ7667 can be used as the LIN bus master as shown in Figure 8-4. As the LIN bus master node, the MAXQ7667 controls all

traffic on the bus. The master sets the communication speed by sending the break and sync sequence. It also sends the identification

field and checksum for specific slaves to respond to.

8.4.4.1 LIN Master Setup Example

To set the master mode, the LIN or UART mode select (LUN[1:0]) bits in CNT0 are set for master mode. To set up the master mode,

the following registers should be set as follows.

• Set the INIT bit (CNT0.2) to 1 to force LIN into initialization state.

• Set the LUN[1:0] bits (CNT0.1:0) to 0x03 to set LIN master mode.

•

Set the AUT bit (CNT0.3) to 1 to enable automatic checksum.

• Set the INE bit (CNT0.4) to 1 to enable interrupts.

•

Set the FP[1:0] bits (CNT0.6:5) to 0 to disable r

eceive filter.

• Set the WU bit (CNT0.7) to 1 to set the peripheral to wake up.

• Set CNT1 to 0x00 to enable transmit.

• Set the CNT2 to 0x00 (default).

• Set SCON to 0x60, i.e., mode 1.

•

Clear the INIT bit (CNT0.2) by setting it to 0, to clear the LIN init state.

• Set BT (0x0320 sets it for 20kBd).

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MAXQ7667 User’s Guide

Figure 8-4. LIN Bus Master Communication

LIN BUS MASTER

LIN

BUS

MASTER TASK

LAVE TASK

RITE

EAD/WRITE

SLAVE TASK

SLAVE NODE 2

EAD/WRITE

LAVE TASK

LAVE NODE 1

READ/WRITE

SLAVE TASK

SLAVE NODE 3

EAD/WRITE

MAXQ7667

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Maxim-integrated MAXQ7667 Bedienungsanleitung Seite 149