Introduction
   Many of the problems of excessive wiring within a car can be resolved by using a serial multiplex bus like CAN or LIN. The LIN (Local Interconnect Network, reference 1) bus is lower in cost and ideally suited to use within a door or in other areas in the car where its limited data rate of 20,000 baud is adequate. The display of external temperature is an application which falls into this category. As a common location for the outside temperature sensor is in a wing mirror, the data often originates from the door. The actual display is, however, within the car some distance away and the LIN bus is eminently suitable to facilitate the connection. A LIN node requires only 3 wires; there is one LIN data line, the other two connections being the positive and negative supplies.