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