Exploring Engineering

Chapter 9, Part 2

Logic and Computers

Implementing Logic Using Electronic circuits

“This endless circulation of theelectric fluid may appear paradoxical,But it is no less true and real, and you may feel it with your hands.”

Allessandro Volta 1745-1827

Electric Circuits

Ohm's Law:

IV

R

Power in an electrical circuitWhere:P is power in wattsV is voltage in voltsI is current in ampers

Where:I is current in ampers,V is voltage in voltsR is resistance in ohms ()

Where:I is current in ampers,V is voltage in voltsR is resistance in ohms ()

Power in an electrical circuit

P V I Where:P is power in wattsV is voltage in voltsI is current in ampers

Electric Circuits Switch Logic

Switch open = input logic state 0 Switch closed = input logic state1 Lamp off = output logic state 0 Lamp on = output logic state1

OR analogue circuit

• Lamp L off (state 0) unless either A or B closed•This is an OR operation.

Can you draw a circuit with an AND operation?

A B

L

NOR (not or) Logic Function

Switch not pressed = input logic state 0Switch pressed = input logic state 1Lamp off = output logic state 0Lamp on = output logic state 1

Input A Input B

Output

Relay Logic

Relay NOR Circuit

• Relay coil not energized = input logic state 0•Relay coil energized = input logic state1•Lamp off = output logic state 0•Lamp on = output logic state1

A input B input

Battery

Vacuum Tubes

Transistors

Inside Transistors

Transistor NOR Circuit

Input A Input B

Battery

Output

•Gate Voltage 0 volts = input logic state 0

•Gate Voltage 5 volts = input logic state 1

•Output Voltage 0 volts = output state 0

•Output Voltage 5 volts = output state 1

Integrated Circuits

Only 7/16" wide and containing two transistors, this unassuming integrated circuit was nevertheless the first. It was mounted on a bar of germanium and was demonstrated by TI on September 12, 1958.

Complex Integrated Circuits

Millions of transistors can be combined on a single chip to create a Central processing Unit

Integrated Circuits can be fabricated to act as storage for program instructions and data.

THE CPU The CPU (Central Processing

Unit) is the complex integrated circuit that makes something a computer.

The CPU is the part of the computer that processes information, performs arithmetic calculations, and makes decisions based on information values.

The instructions and information used by the CPU are stored in computer memory.

CPUProcessorInput

PermanentStorage

Output

TemporaryStorage

Intel 4004 chipIntel 4004 chip

PC Motherboard

The Hardware/Software Connection

The hardware consists of the physical part of the computer: CPU chips, RAM and ROM chips

The software is the program instructions used by the CPU chip.

The hardware function of the computer can be changed by changing the software.

Embedded Systems

An embedded computer is a special purpose computer frequently used to control hardware devices.

Examples: microwave oven, automobile engine control computer.

Examples of Embedded Systems

Personal items such as personal digital assistants (PDAs), mp3 players, mobile phones, videogame consoles, digital cameras, DVD players, GPS receivers, and printers.

Many household appliances, such as microwave ovens, washing machines and dishwashers, are including embedded systems to provide flexibility, efficiency and features.

Advanced HVAC systems use networked thermostats to more accurately and efficiently control temperature that can change by time of day and season.

Home automation uses wired- and wireless-networking that can be used to control lights, climate, security, audio/visual, etc., all of which use embedded devices for sensing and controlling.

Computers in CarsAll 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

Computers in CarsDepending on how expensive your 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

Embedded Computers in Cars

SPEECH TECHNOLOGY LIGHTING SYSTEM ELECTRONIC-MEMORY SEAT ELECTRIC WINDOWS MIRROR CONTROL PREMIUM AUDIO SYSTEM DOOR MODULE CLIMATE CONTROL VEHICLE-T0-ROADSIDE

COMMUNICATIONS RAIN SENSOR ONE-WAY DATA PAGER DIGITAL RADIO HIGH-INTENSITY DISCHARGE

LAMPS NAVIGATION/GPS

ALARM SYSTEMS TRIP COMPUTER HEAD-UP DISPLAY ANALOG AND DIGITAL

INSTRUMENTATION RIGHT-OF-CLUSTER DISPLAY CRUISE CONTROL INTERNET INTEGRATED CELL PHONE CENTRAL-BODY CONTROLLERS CENTRAL LOCKING REMOTE KEYLESS ENTRY TRANSMISSON CONTROLLER

ENGINE CONTROLLER IMMOBILIZATION

Embedded Computers

Typical Car Computer

The computer from a Ford Ranger

Future Cars Future car technology is now wide open. For instance, with

peak oil looming and future shortages of fossil fuels imminent there has been much emphasis lately on cars that run on alternative fuels.

In the longer term, future car technology will most likely involve cars that run on hydrogen, electricity, air, nitrogen, or even nuclear power.

In 1958 the first nuclear automobile was the Ford Nucleon. The Ford Nucleon was a concept vehicle that was supposed to be powered by a small nuclear reactor at the rear of the vehicle fueled by radioactive material. No working prototypes were ever built.

SummaryBoolean algebra is the short-hand

language used for logic Just three operators AND, OR and

NegationBinary is the language of computers

Boolean operators have electrical analogues that are the template for computers