SEE 3223: MicroprocessorsKamal Khalil ROOM : P04 - 125

Ext.: 35277, HP: 0197563004

Email: kamal@fke.utm.my

Department of Microelectronics and Computer Engineering (MiCE)Faculty of Electrical Engineering

Universiti Teknologi Malaysia

Consultation:Tuesday 11:00 – 12:55 a.m.Thursday 11:00 – 12:55 a.m.

MODULE 0

IntroductionPlasticcase

Pins

Chip

Microprocessor SEE3223

AimThis subject introduces the principle and the usage of microprocessor. Few topics that are emphasized are processor architecture, assembly language and basic interfacing in a microprocessor-based systems.

Learning OutcomesAt the end of this course, students will be able to : Describe and differentiate all the component of microprocessor-

based systems. Analyze and design AVR Atmega32 assembly language programs. Analyze and design AVR Atmega32 microprocessor systems. Work with AVR Studio and communicate effectively in a team to

solve complex AVR Atmega32 design problems.

SEE3223 Microprocessor Systems

What’s in this course:– Assembly language programming– Microprocessor concepts and architecture– Hardware interfacing

Pre-Requisites– Number representation, coding, registers, state machines– Realization of simple logic circuits– Integrated circuit technologies– Designing with MSI components– Flip-Flops– Counters and sequential MSI components– Register transfer logic

Course Policy

Attendance is compulsory.

You are responsible for whatever is taught in the lecture. If you miss a class, it is your responsibility to find out about assignment, quizzes and exam from elearning.

Punctuality is expected.

Makeup tests will not be given except in the case of actual emergencies with written evidence.

You are encouraged to collaborate (not copy) on assignment problems with your "study buddies.”

Grading Policy

Assessment Breakdown:

– 4 Quizzes (Best 3 out of 4) = 30%

– 1 Group Assignment = 20%

– Final = 50%

Material

Lecture notesWill be posted

TextbooksMuhammad Ali Mazidi and, Sarmad Naimi and Sepehr Naimi (2010), The AVR Microcontroller and Embedded Systems: Using Assembly and C, 1st Ed., Prentice Hall.

MODULE 1Microprocessor-Based

SystemsPlasticcase

Pins

Chip

Microprocessor-Based Systems

Aims– To review the main elements of a microprocessor system.

Intended Learning Outcomes– At the end of this module, students should be able to:

• Define and explain important terms associated with both hardware and software elements of a microprocessor system

• Tell the difference between general purpose computing and embedded computing

• List down the major components inside a computer & processor• Tell the difference between computer, processor, microprocessor and

microcontroller• Explain instruction execution cycles of a generic microprocessor

Computer Data Processing

Data Storage

What is Computer ?

Basic Functions of Computer

• Data Processing• Data Storage• Data Movement• Control

Microprocessor-Based Systems

20102011-I 12

Whenever the word microprocessor is mentioned, it conjures up a picture of a desktop or laptop PC running an application such as a word processor or a spreadsheet.

While this is a popular application for microprocessors, it is not the only one and the fact is most people use them indirectly in common objects and appliances without realizing it. Without the microprocessor, these products would not be as sophisticated or cheap as they are today.

Microprocessor-Based Systems

20102011-I 13

Computing systems are everywhere. Its probably no surprise that millions of computing systems are built every year destined for desktop computers (Personal Computers, or PCs), workstations, mainframes and servers. What may be surprising is that billions of computing systems are built every year for a very different purpose: they are embedded within larger electronic devices, repeatedly carrying out a particular function, often going completely unrecognized by the devices user. Creating a precise definition of such embedded computing systems, or simply embedded systems, is not an easy task.

Computer Classifications

• Classification of computers:– Servers:

• Big, expensive, available 24x7 (read “24 by 7” or 24 hours a day, 7 days a week. Mainframes are old servers made by IBM.

– Desktops: • computers on your desk

– Laptops: • computers you carry in your bag

– PDA (personal digital assistants): • Miniaturized computers you carry in your pocket

– Embedded systems: • computers that have a specific application!

What is an Embedded System?

20102011-I 15

• a microprocessor-based system• built to control a function or range of functions• not designed to be programmed by the end user in the same way that

a PC is• Usually embedded as part of a complete device including hardware

and mechanical parts

SOFTWARE PROGRAM#include <16f876a.h>#use delay (clock=20000000)#byte PORTB=6main(){set_tris_b(0);portb=255; //decimaldelay_ms(1000);portb=0x55; //hexadecimaldelay_ms(1000);portb=0b10101010; //binarydelay_ms(500);}

System

Embedded System: Example

20102011-I 16

Specific Purpose Processors in Embedded Systems

• Embedded Controllers:– General purpose for any embedded system– Small size, low power, integrated functions– Traffic light system, SCADA system etc.

• Digital Signal Processors:– optimized for MAC operations especially for digital signal processing applications– Commonly found in hand-phones, modems, communications systems, motor driver, CNC

machines etc.

• Graphics Processors:– To speed up graphic processing such as physic calculations, image manipulation etc.– found in graphics cards of workstations and als o integrated with a CPU

• Programmable Logic Controllers:– Optimized for control applications– Usually found in industrial and automation applications

General Purpose Computing vs Embedded Systems

General Purpose EmbeddedIntended to run a fully general set of applications

Runs a single or limited applications often known at design time

End-user programmable Not end-user programmableResources are plenty,Faster is always better

Resources are scarce, operates in fixed run-time constraints, additional performance may not be useful/valuable

Differentiating features:• Speed (need not be fully

predictable)• Cost (eg RM3k vs RM5k per

laptop)• Software compatibility

Differentiating features:• Speed (must be predictable)• Power• Cost (eg RM2 vs RM2.50)• Size• Software compatibility problems

20112012-I 19/Module 1

A Computer System – Simplified View

Control bus

A Computer System – Simplified View

Address bus

Data bus

An embedded system also has the same structure but at a smaller size

CPU Memory Input/Output

Stores and retrieves data

Controls the operation of the computer Performs its data processing functions

Provides internal communication

among CPU, main memory and I/O

Moves data between the computer and its external environment

What is Microprocessor ?

CPU

Central Processing Unit (CPU): Control the

operation of the computer and performs its data

processing functions; often simply referred to as

PROCESSPR

Processor or Central Processing Unit (CPU)

20112012-I 22/Module 1

Registers

Control Unit

ALU

Address Bus

Data Bus

Control BusInte

rnal

Bus

A set of internal storage locations within the CPU

Control & Instruction Registers

Program Counter

User-Visible Registers

Instruction Register

...

General-Purpose Reg.

Address Register

Data Register

Flag Register...

To perform the arithmetic and logical operations within the CPU

To synchronize and control the overall operation of the P system To decode instruction and pass the necessary control signals to CU

Microprocessor – Basic concept

Microprocessor, by-itself, completely useless – must have external peripherals toInteract with outside world

CPU

Control bus

16-bit / 32-bit / 64-bit wide

Timing signals, ready signals,interrupts etc

bidirectional8-bit / 16-bit / 32-bit / 128-bit

Data bus

Address bus

Microprocessor – Basic concept

BootROM

Used at startup

Instruction(program)

ROM

DataRAM

Input/Output

External Comm.

CPU

Address

Control

Data

Microprocessor, by-itself, completely useless – must have external peripherals toInteract with outside world

Memory

Memory Address-1 Memory Address-2

Memory Location-nMemory Address-n

Memory Location-1

Memory Location-2

5 6 7 81 2 3 4

1 byte = 8-bit data 1 word= 2 bytes

1 double = 2 words

Number of addresses 2N (where N is an integer)

Memory Devices• Read-Only Memory

– Non-volatile memory: contents is retained even without power– In embedded systems, used to store application programs and test routines– Contents can be set by fixing it during manufacturing or “burning” it using a

programming device– Common types include MROM, PROM, EPROM and flash memory– Erasable types can only be rewritten a fixed number of times

• Random Access Memory– Contents lost without power (volatile memory)– Used to store temporary data. In embedded system, very little RAM is

required. Some systems don’t even have RAM at all!– No limit to number of writes the device can handle– Fast writes (unlike EPROM/EEPROM)– Two major types are SRAM and DRAM

Data & Address Buses

015

224-1= 8M locations

Address bus 24 bits

0x000000

0xFFFFFF

24-bit address bus

16-bit data bus

Data bus 16 bits

CPU Memory

1. Smallest transferable amount of data from memory to CPU (and vice versa) is one byte.

2. Each byte has a unique location or address.

3. The address of each byte is written in hexadecimal (hex). For AVR, the prefix ‘0x’ means a hex value.

4. The range of addresses accessible by the processor is the memory space. (Limited by the size of the address bus).

5. The Atmega32 (and many other AVR models) does not have direct support for an external memory interface.

20112012-I 28/Module 1

Microcontroller – Basic concept

Microcontroller – Basic concept

Microcontroller - put a limited amount of most commonly used resources inside one chip

BootROM

ProgramROM

DataRAM

Input/Output

ExternalComm.CPU

Address

Control

Data

Microprocessor vs Microcontroller

• Microcontroller:

– A chip that contains all the components of a computer – processor, memory, input/output, and essential peripherals.

– Less flexibility– Less component count in system– Processing power is the same as

long as using same processor

• Microprocessor:

– A chip that contains only the processor

– Need other chips to make a working system

– More flexible– Can have very few I/O or

many I/O devices using the same processor chip

Software• Why we need a program

– When CPU was invented designer use machine code– To simplify work, assembly language was invented.

• Program: – Sequence of instructions that perform tasks

• Computer software– When hardware system was invented their functions are fixed, to make

the system flexible the codes must be changeable (soft).

Machine & Assembly Language• Machine instruction

– A sequence of binary digits which can be executed by the processor, e.g. 0001 1011.– Can only be understood for specific CPU– Hard to understand and easy to forget for human being

• Assembly language– An assembly program consists of assembly instructions– An assembly instruction is a mnemonic representation of a machine instruction e.g.

ADD equivalent to “04H”– Assembly programs must be translated into object code (machine code) before it can

be executed . Known as assembler.– Assemblers can be of two types: cross assembler and native assembler.– Cross assembler runs on one microprocessor and generates machine instructions that

will be executed by another microprocessor that has different instruction set, e.g. freeware ASM68K.

– Native assembler runs and generates instructions for the same microporcessor. – Drawbacks of assembly programs are:

• dependent on hardware organization, difficult to understand long programs, low programmer productivity

High-level language (HLL)• High-Level Language

– Syntax of a high-level language instructions are closer to human language.

– A translator is required to translate the program written in a high-level language into object code – known as a compiler.

– There are cross compilers that run on one computer but translate programs into machine instructions to be executed on a computer with a different instruction set.

– Main drawback is the generated machine code is longer compared to writing using assembly language.

– System speed requirements may be hard to be fulfilled.– Shorter development time compared to assembly– So, C language has been extensively used in microcontroller

programming in industry.

Instruction Cycle (Fetch-Execute)

• The processor executes instructions one-by-one according to the sequence found in memory

• Everything is controlled by, what else, the control unit in the CPU.• To execute an instruction, the processor must fetch it from

memory.• Each instruction is processed in instruction cycle or the fetch-

execute cycle

Fetch Execute

Instruction Cycle Details

• Fetch phase:1. Read the instruction and put it into the instruction register (IR)2. Control unit decodes the instruction; updates the PC for the

next instruction

• Execute phase:3. Find the data required by the instruction.4. Perform the required operation.5. Store the results.6. Repeat from Step 1.

How computers work

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Review Questions 1

Review Questions 2

Review Questions 2 (Cont’d)

Selecting a Microprocessor

• Choose the right one for your application– Primary criteria: Cost, Power, Size, Speed– Others: package options, integrated peripherals, potential for future growth

• Choose one with good software development support– development environment - good compiler and debugger availability– evaluation boards– in-circuit emulators for those with deep pockets– Operating system availability

• Other considerations– Code density: affects power consumption, performance and system cost– Hardware availability: make sure you can actually purchase the microcontroller

before designing it in– Prior expertise, licensing, etc

Summary

• Microprocessors and embedded controllers are a ubiquitous part of life today

• Concept of a microprocessor & microcontroller• Understand how a µP works• Headhunters report that EEs familiar with µC, µP design are in the

highest possible demand• Web Resources:

– How Microprocessors Work:• http://computer.howstuffworks.com/microprocessor.htm• http://www.intel.com/education/mpworks/• http://www.cse.psu.edu/~cg471/03f/hw/pj5/how-micro.html

– Great Microprocessors of the Past and Present:• http://www.sasktelwebsite.net/jbayko/cpu.html

– Great Moments in Microprocessor History:• http://www-128.ibm.com/developerworks/library/pa-microhist.html