Local Interconnect Network (LIN)

Local Interconnect Network (LIN) is a low-cost, low-speed serial communication bus designed specifically for automotive distributed electronic systems. Developed to complement high-speed buses like CAN, LIN typically serves as a sub-bus in simpler control applications where high bandwidth and system complexity are unnecessary.

To put it simply: if CAN represents the main arterial highway linking a vehicle's vital organs, LIN acts as the capillary network reaching its nerve endings.

Technical Principles and Key Features

The LIN bus was established in 1998 by the LIN Consortium—a joint initiative between carmakers like Audi and BMW and semiconductor specialists such as Motorola—to create a standardised, open, and cost-effective solution for less demanding applications.

Its core technical features include:

• Single-Master/Multi-Slave Architecture: A LIN network comprises one master node and multiple slave nodes. All communications are initiated by the master node and answered by slave nodes, eliminating the need for complex bus arbitration mechanisms.

• Extremely Low Cost: Based on standard UART/SCI serial interfaces, virtually all microcontrollers feature the required hardware natively. Slave nodes can even dispense with costly quartz crystal oscillators and synchronise their clock directly from the master node's Sync Field, significantly cutting production costs.

• Single-Wire Transmission: Utilises a single 12V signal wire, effectively reducing wiring harness bulk and weight.

• Low-Speed Communication: Operates at a maximum data transfer rate of 20 kbit/s, with a maximum bus length of 40 metres.

Application Scenarios

The LIN bus primarily caters to body comfort and convenience systems with low real-time demands and small data volumes. Typical applications include:

• Doors and Windows: Power window operation (including anti-pinch function), door locks, and central locking control.

• Seats and Mirrors: Electric seat adjustment, wing mirror power-folding, and mirror heating.

• Lighting and Air Conditioning: Cabin ambient lighting, signal light controls, and air-con vent/damper actuators.

• Sensors and Actuators: Rain sensors, smart wipers, cabin temperature sensors, and other auxiliary units.

By striking an ideal balance between cost and performance, the LIN bus works hand-in-hand with CAN to form the backbone of modern automotive hierarchical network architectures. In a standard vehicle setup, high-speed CAN manages mission-critical powertrain and chassis systems, while multiple LIN sub-networks operate non-safety-critical body control modules throughout the vehicle.