AN4101

Introduction to the LIN bus

Doc ID 23127 Rev 1

5/21

2

Introduction to the LIN bus

2.1

LIN consortium

The LIN consortium was created in 1998 to standardize serial communication in automotive

applications. LIN complements CAN as a cost-effective subnetwork. You can get your LIN

specification version at http://www.lin-subbus.org/.

The key features of LIN are as follows:

●

●

speed up to 20 Kbps, acceptable for many applications (limited for EMI reasons)

●

a single master, multiple slave concept, without need for arbitration

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low-cost silicon implementation based on UART

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self-synchronization of slave nodes, allowing low-cost inaccurate clock source usage

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guaranteed latency times for signal transmission, allowing predictable system design

This low-price serial communication protocol replaces CAN in various non safety-critical

automotive applications (for example, in the body, door, roof or seat). LIN node functionality

mainly involves switches, actuators and sensors.

2.2

LIN principle

The master node decides when and which frame shall be transferred on the bus. Slave

nodes simply react when they detect a Break on the bus.

The master node has control over the whole bus and protocol. It decides which message at

what time is to be transferred over the bus. It also does the error handling.

For this, the master:

●

sends the Header, which consists of a Break, a Synch byte and an Identifier field

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monitors data bytes and checksum bytes to evaluate them for consistency

●

is the reference for the clock base

The slave node receives or transmits data when an appropriate identifier is sent by the

master.

For this, the slave:

1.

checks the identifier

2.

depending on the identifier value, determines which of the following to do:

–

receive data

–

transmit data

–

do nothing

Note:

When transmitting, the slave sends from 1 to 8 data bytes, and 1 checksum byte.