Car Computers

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					Car Computers

By Justin Algarin CIS 101 MWF 9:00-9:50

Innovation of the Car Computer
 Before emissions laws were enacted, it was possible to build a car engine without microprocessor. With the enactment of increasingly stricter emissions laws, sophisticated controls were needed to regulate the air/fuel mixture so that the they could remove a lot of the pollution from the exhaust.

History of the Microprocessor
 A microprocessor -- also known as a CPU or central processing unit -- is a complete computation engine that is fabricated on a single chip.  The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very powerful -- all it could do was add and subtract, and it could only do that 4 bits at a time.

 But it was amazing that everything was on one chip. Prior to the 4004, engineers built computers either from collections of chips or from discrete components.

What is a Microprocessor?
 The microprocessor is the heart of any normal computer, whether it is a desktop machine, a server or a laptop.

How does the computer work?
 Controlling the engine is the most processor-intensive job on your car, and the engine control unit (ECU) is the most powerful computer on most cars.

How the ECU Works
 The ECU uses closed-loop control, a control scheme that monitors outputs of a system to control the inputs to a system, managing the emissions and fuel economy of the engine as well as many other things.

ECU Jobs
 The ECU gathers data from dozens of different sensors.  The ECU knows everything from the coolant temperature to the amount of oxygen in the exhaust. With this data, it performs millions of calculations each second, including looking up values in tables, calculating the results of long equations to decide on the best sparking time and determining how long the Fuel injector is open.

ECU Jobs (contd.)
 The ECU does all of this to ensure the lowest emissions and best mileage.

ECU Design
 A modern ECU might contain a 32-bits, 40MHz processor.  The code in an average ECU takes up less than 1 megabyte (MB) of memory.

 The ECU sends information to a central module, which stores the faults and can communicate them to an off-board diagnostic tool.

The End

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