In the late 1990s, five car makers, a communications tools manufacturer, and what is now Freescale Semiconductor founded the LIN Consortium to develop a low-cost automotive communications standard. The local interconnect network (LIN) is the UART-based, single master, multiple-slave networking architecture that was developed for automotive sensor and actuator networking applications. LIN provides a low-cost networking solution for connecting motors, switches, sensors, and actuators in the vehicle.

The LIN master node typically connects the LIN network with higher-level networks, like the controller area network (CAN), extending the benefits of networking all the way to the individual sensors and actuators.

LIN and SAE J2602 background
Since the first major release of the LIN specification (version 1.3) in November 2002, significant changes have been made to the standard. The resulting revision, 2.0 of the specification, was released in September 2003. The figure below shows the substantial changes in the specification, but both versions are still in use by many manufacturers.

Many communications standards only specify protocol information, often referred to as the data link layer of the protocol. A good example of this is the Bosch CAN 2.0b specification. There are also additional specifications for physical interfaces (sometimes called the physical layer), such as the Society of Automotive Engineers (SAE) standard J2284 for the high-speed physical layer for CAN. LIN defines these two elements as part of the specification, as can be seen above, but also includes specifications for software and tools interfaces. By including these significant standardized components, LIN is a very comprehensive specification.

A task force of SAE's Vehicle Architecture for Data Communications Standards Committee also looked at the LIN specification for use in North American vehicles. This task force, SAE J2602, developed recommended practices for the use of LIN. This J2602 specification is based upon LIN 2.0, but reduced the complexity of some software elements of the specification in an effort to reduce the size and complexity of embedded software required in LIN slave nodes. The figure below shows how these two standards are related.

Although software may vary in embedded LIN and SAE J2602 slaves, they are both based upon the same protocol specification so the microcontroller technologies used for both remain consistent. This consistency allows both standards to work together to drive total hardware volumes up and costs down.

There is a wide range of 8-bit microcontrollers to implement LIN devices, from very simple LIN slaves to complex master nodes. The choice of microcontroller will vary based on performance and cost.