A LIN cluster (LIN Network) is composed of a number of LIN nodes which are interconnected via a physical transmission medium (LIN Bus) (see figure “LIN Network”). The goal of cost-effective communication for serial data exchange in the non-safety-critical sensor/actuator field was achieved primarily at the cost of eliminating an independent communication controller. The microcontroller is used to implement the LIN communication. The physical bus interface is realized by a LIN transceiver. Equally affected by cost-saving efforts is the method for physical signal transmission: it is now on a single-wire line (Single Wire).

Because of the lack of a communication controller, serial data transmission in a LIN cluster is handled via the microcontroller’s serial interface (Serial Communication Interface — SCI) and is byte-oriented. Each byte is transmitted by the SCI with the LSB (Least Significant Bit) first and is framed by a start bit and a stop bit (SCI frame). Essentially, a LIN frame is made up of a number of SCI frames (see figure “LIN Frame”).

Meanwhile, microcontrollers with ESCI (Enhanced SCI) or LIN SCI are also available. These modified SCIs relieve the microcontroller considerably in the LIN communication. The most important task of the LIN transceiver is to adapt the logical level to the physical bus level. The LIN transceiver is equipped with a driver for sending, a section for receiving and a logic for sleep and wake-up.

The maximum data rate is limited to 20 kbit/s to keep radiated emissions within limits. At line lengths of up to 40 meters, a maximum recommended node count of 16 is based on node and line capacitances as well as the maximum allowable time constant of a LIN cluster defined by the LIN specification.