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MTECH[CAD/CAM]

Microprocessor GenerationsFirst generation: 1971-78

Behind the power curve (16-bit, <50k transistors)

Second Generation: 1979-85Becoming “real” computers

(32-bit , >50k transistors)Third Generation: 1985-89

Challenging the “establishment” (Reduced Instruction Set Computer/RISC, >100k transistors)

Fourth Generation: 1990-Architectural and performance leadership

(64-bit, > 1M transistors, Intel/AMD translate into RISC internally)

IntroductionFocus on microprocessors as general purpose,

flexible and reconfigurable controllers and the ways sensors and actuator relate to these.

Microprocessors are often called microcontrollers What is a microprocessor? What is the different

between a microprocessor and a computer or a microcomputer and how a distinguishing set of features is arrived at are all difficult and subjective issues. What is a microprocessor to one is a full fledged computer to another

The microprocessormicroprocessor is a stand alone, self contained single

chip microcomputer. It must have as a minimum:

a central processing unit (CPU)nonvolatile and program memory input and output capabilities.

A structure that has these can be programmed in some convenient programming language

can interact with the outside world through the input/output ports.

MICROPROCESSOR

MICROPROCESSOR

The microprocessor• Other important requirements:

• must be relatively simple• reasonably small • necessarily limited in most of its features – memory,

processing power and speed, addressing range and, of course in number of I/O devices it can interact with.

• The designer must have access to all features of the microprocessor – bus, memory, registers, all I/O ports,

• In short, Microprocessors are components with flexible features that the engineer can configure and program to perform task or a series of tasks.

The microprocessor• Two limits on the tasks microprocessors can perform:• The limitations of the microprocessor itself• The imagination (or capabilities) of the designer.

The 8 bit microprocessorWe will narrow down to 8 bit microprocessors

these are the most common in sensor/actuator systems they are simple and representative of all microprocessor

16 and 32 bit microprocessors exist There are a number of architectures being used. We will emphasize the Harvard architecture because

of its simplicity, flexibility and popularity.

Addressing8 bit microprocessors have word length of 8 bits. Integer data from 0 to 255 may be represented directly. To address memory, usually a longer word is needed. Most microprocessor have a 12 bit (4k) 14 (16k) or 16 bit

(64k) memory address but longer address words are also used.

SpeedMost microprocessor operate at clock speeds between 1

and 40 MHz. Since often the clock is internally divided, the instruction

cycle is slower than that Typical values are up to about 10 MHz cycle clock or 0.1

s per instruction

Input and outputInput and output is defined by the availability of pins

on the package. Usually limited to less than about 100 pins (6, 8, 14,

18, 20, 28, 32, 40, 44, 64 and 100 pins are common). Two pins are used to power to the device For example, an 18 pin device can have no more than

14 I/O pins. Of these, some may be used for other purposes such

as oscillators or communication

Clock and timersMicroprocessors have internal timers

under the control of the user used for various functions requiring counting/timing At least one counter is available larger microprocessors can have 4 or more timerssome are 8 bit timers and some 16 bit timers. a watchdog timer is available for the purpose of resetting

the processor should it be “stuck” in an inoperative mode.

Other functionalities• Many microprocessors provide multiple interfaces, all

under the user’s control. • Other functions such as analog amplifiers and even

transceivers are sometimes incorporated within the chip. • The I/O used for these functions are either digital I/O (for

communication for example) or analog

Programs and programmabilitymicroprocessor is only useful if it can be

programmed. Programming languages and compilers have been

designed specifically for microprocessors. The basic method of programming microprocessors is

through the Assembly programming languageCan be, and very often is done through use of higher

level languages with C leading.