automotive electronics

In automotive electronics networking, the commonly networking standard used is called CAN or controller area network which uses a baud rate of up to 1Mbps. This speed is needed in the control of engine and other critical components of the automobile that requires fast transfer of information. However, there are some areas of control which does not require that kind of speed and hence a slower speed standard can be utilised to save control cost. Some of these areas are the mirrors control, Window lift, seat control and door lock amongst others.

Due to this requirements, a consortium was formed in 1998 consisting of 5 automotive manufacturers (Volvo, BMW, Audi, VW and Daimler-Chrysler), 1 tool supplier (VCT) and 1 semiconductor supplier (Motorola) to look into this. As a result, the LIN (Local Interconnect Network) specifications was finalised on 2 February 2000. The first version of LIN was 1.1 and currently version 2.0 is in use. The most recent development
in LIN is the use of it over the vehicle's battery line using a DC-LIN transceiver. Some of the main features of LIN are listed below.

* One master and up to 16 slaves. No collision detection feature is needed as master initiated all messages communication with slaves. The master is usually implemented with a more powerful microcontroller compared to the slaves as it has to handle more tasks.

* Baudrate of up to 20kbps. Slower speed is chosen to reduce the effect of electromagnetic interference.

* Single wire implementation based on enhanced ISO 9141.

* Simple SCI or UART hardware interface which is available in most microcontroller chips making its implementation cost effective.

* Self synchronization in the slave nodes without the need to have crystal or ceramic resonator. Internal RC oscillator for the microcontroller is good enough and hence making its implementation lower cost.