Computers in your car!

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Last week in Tech-Talk we took a look at some technology beyond your windscreen- ANPR technology and how it affects you, the motorist. This week we’re going to look a little closer to home- your car!

Technology’s come a long way since the invention of the automobile, while you may know your steering from suspension, do you know your ECU from your Body controller chip?

There may be up to 50 microprocessors inside your car, controlling functions as vital as spark timing, to emissions controllers to the indicator lights on your dash.

Lets take a deeper look at the most important microprocessor lurking deep under the bonnet of a modern car, the Engine Control Unit.

The ECU
The ECU is responsible for many operations including managing emissions and fuel economy by deciding spark timings and determining how long to leave the fuel injector open. This is done used a closed-loop control scheme which analyses and computes the output levels of the system to feed back into the inputs. The ECU has many sensors monitoring many components of your engine. It’s even aware of the intimate details surrounding the current state of your exhaust.

ECU Components

Analog-to-digital converters (ADCs)
ADCs are responsible for converting analog values (voltages) to a digital quantity (represented as a series of 1’s and 0’s), so they may be analysed and computed by a microchip. An example of an analog sensor that would be connected to an ADC on the ECU is an oxygen sensor.

Digital-to-analog converters (DACs)
A DAC is responsible for the exact opposite as an ADC. It converts a digital value computed by the ECU to an analog voltage to be applied to part of your engine. Your home stereo also has a DAC in order to play the digital information stored on a CD on your analog speakers!

Digital Outputs
Your modern day car used the ECU to fire spark plugs and open or close the fuel injectors. Digital outputs enable this functionality. By the very nature of the word “digital” – these outputs are either on (1), or off (0). Digital outputs work in conjunction with transistors. The digital output provides a current the transistor, which is then able to supply a much larger current to the component in question.

Signal Conditioners
Responsible for adjusting analog signals before the ADC’s reads them. If a ADC reads voltages between 0V - 5V and the oxygen sensor outputs a signal between 0V - 1.1V a signal conditioner is needed to bring the levels in to line to maintain compatibility.

Lots of long words and jargon to get your head round there! But believe it or not, this is not the end of the story of an ECU! Next week we’ll take a look at the communications features an ECU provides, how they make your car cheaper and how and why your local garages connect their laptops to your car to give it a health check.