What are vehicle computers called?

Automotive control system

This article is about controls for motor vehicles. For other uses, see Control unit (disambiguation)

An ECU from a Geo Storm

For other uses, see ECU

An electronic control unit (ECU), also known as an electronic control module (ECM), is an embedded system in automotive electronics that controls one or more of the electrical systems or subsystems in a car or other motor vehicle.

Modern vehicles have many ECUs, and these can include some or all of the following: engine control module (ECM), powertrain control module (PCM), transmission control module (TCM), brake control module (BCM or EBCM), central control module (CCM), central timing module (CTM), general electronic module (GEM), body control module (BCM), and suspension control module (SCM). These ECUs together are sometimes referred to collectively as the car's computer though technically they are all separate computers, not a single one. Sometimes an assembly incorporates several individual control modules (a PCM often controls both the engine and the transmission).[1]

Some modern motor vehicles have up to 150 ECUs.[2] Embedded software in ECUs continues to increase in line count, complexity, and sophistication.[3] Managing the increasing complexity and number of ECUs in a vehicle has become a key challenge for original equipment manufacturers (OEMs).

Types

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Key elements

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• Core
  • Microcontroller
• Memory
  • SRAM
  • EEPROM
  • Flash
• Inputs
  • Supply Voltage and Ground
  • Digital inputs
  • Analog inputs
• Outputs
  • Actuator drivers (e.g. injectors, relays, valves)
  • H bridge drivers for servomotors
  • Logic outputs
• Communication links
  • Housing
  • Bus Transceivers, e.g. for K-Line, CAN, Ethernet
• Embedded Software
  • Boot Loader
  • Metadata for ECU and Software Identification, Version Management, Checksums
  • Functional Software Routines
  • Configuration Data

Design and development

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The development of an ECU involves both hardware and software required to perform the functions expected from that particular module. Automotive ECU's are being developed following the V-model.[1] Recently the trend is to dedicate a significant amount of time and effort to develop safe modules by following standards like ISO 26262.[5] It is rare that a module is developed fully from scratch. The design is generally iterative and improvements are made to both the hardware and software. The development of most ECUs is carried out by Tier 1 suppliers based on specifications provided by the OEM[citation needed].

Testing and validation

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As part of the development cycle, manufacturers perform detailed FMEAs and other failure analyses to catch failure modes that can lead to unsafe conditions or driver annoyance. Extensive testing and validation activities are carried out as part of the Production part approval process to gain the confidence of the hardware and software. On-board diagnostics or OBD help provide specific data related to which system or component failed or caused a failure during run time and help perform repairs.

Modifications

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Some people may wish to modify their ECU so as to be able to add or change functionality. However modern ECUs come equipped with protection locks to prevent users from modifying the circuit or exchange chips. The protection locks are a form of digital rights management (DRM), the circumventing of which is illegal in certain jurisdictions. In the United States for example, the DMCA criminalizes circumvention of DRM,[6] though an exemption does apply that allows circumvention the owner of a motorized land vehicle if it is required to allow diagnosis, repair or lawful modification (ie. that does not violate applicable law such as emissions regulations).[7]

References

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All cars manufactured today contain at least one computer. It is in charge of monitoring engine emissions and adjusting the engine to keep emissions as low as possible. The computer receives information from a many different sensors, including:

• The oxygen sensor

• The air pressure sensor

• The air temperature sensor

• The engine temperature sensor

• The throttle position sensor

• The knock sensor

• The oxygen sensor

Using the information from these sensors, the computer can control things like the fuel injectors, spark plugs and the idle speed to get the best performance possible from the engine while keeping emissions low. The computer can also sense when something has gone wrong and can inform the driver with the "Check Engine" light. A mechanic can read a diagnostic code from the computer and fix the problem.

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Depending on how expensive the car is, there can be all sorts of other computers. For example:

• There is probably a computer controlling the automatic transmission

• If the car has anti-lock brakes , there is a computer reading the wheel speed and controlling the brakes

• Many air bag systems have their own computers

• A car with keyless entry or a security system has a computer for these systems

• Advanced climate control systems often have computers

• Some cars now have motorized seats and mirrors that can remember the settings for multiple drivers, and these contain computers

• Any radio or CD player with a digital display contains a computer of its own

• Cruise control systems use computers

In other words, a modern luxury car is a rolling computer network. It is amazing how many embedded controllers a car can have.

So what was the deal about whether our cars would start on January 1, 2000? Nothing. The computers in our cars have no idea what today's date is because it is irrelevant to their calculations. If you take the battery out of your car to replace it, all of the computers lose power. Your radio, for example, may forget its preset stations. However, you don't have to reset the date on any of these embedded computers because none of them care.

Here are some interesting links:

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