Datasheet

Application Note

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LIN

Background

The Local Interconnect Network (LIN) bus was developed by

the LIN consortium in 1999 as a lower cost alternative to the

CAN bus for applications where the cost, versatility, and speed

of CAN were overkill. These applications typically include

communications between intelligent sensors and actuators

such as window controls, door locks, rain sensors, windshield

wiper controls, and climate control, to name a few.

However, due to its electrical noise tolerance, error detection

capabilities, and high speed data transfer, CAN is still used

today for engine timing controls, anti-lock braking systems,

power train controls and more.

How It Works

The LIN bus is a low-cost, single-wire implementation based

on the Enhanced ISO9141 standard. LIN networks have

a single master and one or more slaves. All messages are

initiated by the master with only one slave responding to each

message, so collision detection and arbitration capabilities

are not needed as they are in CAN. Communication is based

on UART/SCI with data being sent in eight-bit bytes along

with a start bit, stop bit and no parity. Data rates range from

1 kb/s to 20 kb/s. While this may sound slow, it is suitable for

the intended applications and minimizes EMI. The LIN bus is

always in one of two states: active or sleep. When it’s active,

all nodes on the bus are awake and listening for relevant bus

commands. Nodes on the bus can be put to sleep by either

the Master issuing a Sleep Frame or the bus going inactive for

longer than a predetermined amount of time. The bus is then

awakened by any node requesting a wake up or by the master

node issuing a break ﬁeld.

LIN frames consist of two main parts, the header and

the response. The header is sent by the master while the

response is sent by the slave. The header and response each

have subcomponents as shown in Figure 33.

Figure 33. The structure of a LIN frame.

Frame

Header

Break Field Sync Field Data 1 Data 2 Data N Checksum FieldIdentifier Field

Response

Response Space