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ECE-362Microprocessor Systems and

Interfacing

Dr. Abdelrahman Abdelazim

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Module 1 MicrocontrollerProgramming Techniques

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Module 1

Learning Outcome: An ability to program a

microcontroller to perform various tasks

A. Microcontroller Architecture and Programming

Model

B. Microcontroller Instruction Set Overview

C. Assembly Language Programming Techniques

Control Structures

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Module 1

D. Assembly Language Programming Techniques

Control Structure Applications

E. Assembly Language Programming Techniques

Parameter Passing

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Module 1-A

Microcontroller Architecture

and Programming Model

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Reading Assignment: Lecture Note

Week 1

Learning Objectives:

List differences in world views regarding the

role of microprocessors

Define characteristics that distinguish

microprocessors

Describe the PIC16F87XA architecture andprogramming model

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Reading Assignment: Lecture Note

Week 1

Learning Objectives:

List differences in world views regarding the

role of microprocessors

Define characteristics that distinguish

microprocessors

Describe the PIC16F87XA architecture andprogramming model

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Outline

Characteristics that distinguish

microprocessors

Taxonomy of microprocessors from an

application viewpoint

Basic architecture of the PIC16F877A

Instruction formats and data types of thePIC16F877A

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Introduction

Two basic world views regarding the role of

microprocessors are applicable

general-purpose view :a microprocessor is an integral part

of a machine that runs shrink-wrapped software (or onwhich user-programmed applications can be shrink-

wrapped software (or on which user-programmed

applications can be developed and run)user

programmable

embedded view : a microprocessor is a basic digital system

building block that can be used to build intelligent

productsnon-user-programmable

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Introduction

Why this distinction is important:

different architectural/organizational characteristics of

microprocessors can make them more/less suited

for a given application the goodness or badness of a particular

microprocessor can only be evaluated in the

context of the intended application

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Microprocessor Control Systems

Digital control systems are designed to allow a particular set of logical

operations to be carried out. Digital electronic circuits, using logic gates,

can be used to control many devices.

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Hardwired Systems

Systems using logic gates are simple to design and are cheap and

easy to assemble in circuits. Individual chips can be interconnected to

provide complex control functions.

For example, D-type latches on their own are limited in their

capabilities, but with other identical chips can be made to produce

binary counters, shift registers and latches.

This type of circuit is known as Hardwired.

Hardwired systems can be made either by using individual components

(Integrated Circuits or ICs) on a Printed Circuit Board (PCB) or

produced directly in a customised IC.

Drawback is that once a system is designed and manufactured, it

cannot be changed without redesigning the hardware used.

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Microprocessor Control Systems

Consider a customer buying a cup of coffee from a vending machine.

The customer pays, chooses the type of drink and places an empty cup

underneath the dispenser.

The machine detects the cup and fills itwith coffee, dispensing the exact amount

to fill the cup. This ensures that the cup is

not overfilled and that deliberate attempts

to fill larger cups are prevented.

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Hardwired & Software Controlled System

Consider that the manufacturer of the vending machine has decided

that the cup size being used is too small. All the vending machines

need to be updated to use the new size cups.

If a hardwired design had been used,

replacement or modification of the

hardware in each machine would be

required. This would be expensive.

If the machines are software controlled,

the software could simply be replaced or

modified at minimal cost.

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Below is a list of advantages and disadvantages of hardwired systems:

Simple to make, quickly and cheaply.

Hardwired systems cannot easily be upgraded or modified without

changing components.

Relatively easy to understand and gives a predicable output.

Hardwired systems usually have faster speeds of operation than

software controlled systems.

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Below is a list of advantages and disadvantages of software controlled

systems:

Versatile and can be used in a number of different applications.

Function can be modified by changing its program code in situ.

Can be more expensive to produce than hardwired systems

for simple projects.

Can contain errors (bugs) which cause unpredictable results.

Require greater amounts of testing due to the added complexity

of the system.

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A) Speed is slower than software systems

B) Expensive to make

C) Difficult to change function

D) Slow to assemble

Which of the following is a disadvantage of hardwired systems?

Question

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A) Versatile

B) Less expensive to produce than hardwired systems

C) Does not require extensive testing

D) Works reliably first time

Which of the following is an advantage of software based control

systems?

Question

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Structure of a Microprocessor System

This diagram represents a very simple microprocessor system.

As you can see, this is similar to the simple Input - Process - Output

system diagram:

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Microprocessor systems have the ability to connect to several input and

output devices at the same time.

Inputs might include: mouse, keyboard, scanner.

Outputs might include: screen, loudspeaker, printer.

Some of these input and output devices are built into the system.

Others have to be plugged in to the system. Where an input or output

device is plugged in, it is accessed by the computer through a port.

Some devices that are plugged into computers are both inputs and

outputs: a modem for example both transmits and receives data.

There are several different types of port. Some transmit data serially

while others transmit data in parallel, for example, RS232 (serial),

Centronics (parallel), USB (Serial).

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The processor connects to several input and output ports, as well

as memory, at the same time.

This requires a more complex connection system.

The processor needs to be able to select which sub-system it needs to

talk to, decide whether it is sending or receiving, and then send or

receive data.

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The connection system

uses three buses.

The address busgoes

from the CPU to the

memory and input / outputports.

Each sub-system that the

CPU connects to has a unique address.

The CPU sends the address on the

address bus to identify the subsystem it

needs to connect to.

The control busdetermines whether the data is to be sent or received.

The data can then be transmitted along the data bus.

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A bus is just one or more conductors connecting the sub-systems

together.

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A) Address bus

B) Serial Port

C) Control bus

D) Data bus

Which connection system carries the signal that determines whether data

is to be written to or read from, memory?

Question

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Single Chip Microprocessor Systems

A microcontroller is a single IC

containing a central processing

unit, memory, input / output ports

and internal clock.

Microcontrollers provide a one-

chip design instead of requiring

several separate components.

Microcontrollers are used in

domestic appliances, automobiles,electronic locks, security devices,

smart cards, timers, and serial

communication.

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A) Peripheral Intelligent Connector

B) Peripheral Interface Connector

C) Peripheral Interface Controller

D) Peripheral Intelligent Connector

What do the initials PIC stand for?

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A) 2000 - 2003

B) 1997 - 2000

C) 1995 - 1997

D) 1990 - 1995

Approximately, when did PIC use increase dramatically?

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Microprocessor Architectures

Two types of architectures used in modern processors. Von Neumann

architecture used in the Z80 to the modern Pentium chips.

PIC devices use the Harvard architecture. Differs from the Von

Neumann type by having separate memories for program code and

data, so can be accessed independently and simultaneously.

Von Neumann system stores data and program code together in one

memory space. Disadvantage of only allowing the CPU to access

either data or the program memory at any one time.

Advantage of the Harvard architecture is that it reduces the time

taken to retrieve the instructions, and so is more efficient.

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A) Z80

B) Harvard

C) Von Neumann

D) Pentium

What is the name of the architecture used in PICs?

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A) Harvard

B) Von Neumann

C) Z80

D) Pentium

Which architecture system stores program code and memory

code in different locations?

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A) Von Neumann

B) Pentium

C) Z80

D) Harvard

Which is the more efficient architecture for microcontrollers?

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Instruction Sets

Language used by the microcontroller is

divided into a number of instructions.

The Instruction Setdetermines

what functions the microcontroller

can perform and how instructions

need to be written.

This list of instructions is called

the instruction set.

Architecture of microcontrollers

may be further classified into the

types of instruction sets they use.

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A) A notice

B) An instruction

C) A message

D) A function

In order to get a microcontroller to do something, what must

we give it?

Question

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Instruction Sets

CISC (Complex Instruction Set Computer)

Microcontrollers and microprocessor systems which use CISC systems,

have a large quantity of very detailed instructions.

RISC (Reduced Instruction Set Computer)

A reduced instruction set is made up of a small number of key

instructions. PICs use this type of instruction set and have about 35

instructions.

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CISCs have a large number of detailed instructions. Is

this true or false?

Answer True or False.

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Approximately how many instructions can a PIC chip

programmed using RISC understand?

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Social and Economical Benefits

Microcontrollers have many advantages over microcomputers, primarily

because of the reduction in external components. This provides the

following benefits:

Reduction in costs - smaller number of components required.

Increased system reliability - fewer components mean a smallerlikelihood of the system failing.

Reduced power consumption - fewer components mean less powerrequired for the system.

Program Code can be upgraded, in situ, - programs can be written tothe PIC while in a system.

Reduced Electromagnetic emissions - having fewer componentsreduces the electromagnetic emissions produced by a device.

Size - the small size of a microcontroller enables it to be usedin small devices.

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A) Increased reliability

B) Reduced costs

C) Increased portability

D) Reduced number of components

A microcontroller has one main advantage over a

microcomputer, which gives rise to many benefits. What is

it?

Question

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