How Car Computers Work

­C­lusters are now being used on a smaller scale for sensors. For instance, a traditional pressure sensor contains a device that outputs a varying voltage depending on the pressure applied to the device. Usually, the voltage output is not linear, depends on the temperature and is a low-level voltage that requires amplification.

Some sensor manufacturers are providing a smart sensor that is integrated with all the electronics, along with a microprocessor that enables it to read the voltage, calibrates it using temperature-compensation curves and digitally outputs the pressure onto the communications bus.

This saves the carmaker from having to know all the dirty details of the sensor, and saves processing power in the module, which otherwise would have to do these calculations. It makes the supplier, who is most up on the details of the sensor anyway, responsible for providing an accurate reading.

Another advantage of the smart sensor is that the digital signal traveling over the communications bus is less susceptible to electrical noise. An analog voltage traveling through a wire can pick up extra voltage when it passes certain electrical components, or even from overhead power lines.

Communication buses and microprocessors also help simplify the wiring through multiplexing. Let's take a closer look at how they do this.