Intro to Microcontrollers - Md. Atiqur Rahman Ahad

Microprocessor
–

Intro!

Md. Atiqur Rahman Ahad

Introduction to Microcontrollers

Parts of computer: CPU, memory, I/O

•
CPU: Control and data path

•
Memory: Stores instruction and data

•
Input/output: Interact with the outside of
computers

Why Study Microprocessor
Design?

Why Study Microprocessor Design?



°
(as reported in Microprocessor Report, Vol 13, No. 5)

•
Emotion Engine: 6.2 GFLOPS, 75 million polygons per second

•
Graphics Synthesizer: 2.4 Billion pixels per second

•
Claim:
Toy Story
realism brought to games!

Sony Playstation 2000

Why Study Microprocessor Design?


Wireless Sensor Networks Platform

Power Metering Application

Microcontrollers vs Microprocessors

•
A microprocessor is a
CPU on a single
chip.

•
If a microprocessor, its associated support
circuitry, memory and peripheral I/O
components are implemented
on a single
chip
, it is a
microcontroller
.

What is an Embedded System?

•
A combination of computer hardware and
software, and perhaps additional mechanical
or other parts, designed to perform a dedicated
function.

•
In some cases, embedded systems are part of a
larger system or product, as is the case of an
anti
-
lock braking system in a car. Contrast
with general
-
purpose computer.

•
Examples range from washing machines,
cellular phones to missiles and space shuttles.

•
Embedded Systems

–
Operations managed behind the scenes by a
microcontroller

•
Microcontroller (MCU)

–
An integrated electronic computing device that
includes three major components on a single
chip

•
Microprocessor (MPU)

•
Memory

•
I/O (Input/Output) ports


What is an Embedded System?

•
Electronic devices that incorporate a
computer (usually a microprocessor) within
their implementation.

•
A computer is used in such devices
primarily as a means to simplify the system
design and to provide flexibility.

•
Often the user of the device is not even
aware that a computer is present.

Killer

apps!

•
Communications


network routers, switches,
hubs.

•
Children’s toys


•
Fuel injection control, passenger environmental
controls, anti
-
lock braking systems,

•
Air bag controls,

•
GPS mapping.

•
Automotive Navigation systems, automatic landing
systems, flight attitude controls,

•
Engine controls, space exploration ……..

Where are the embedded devices?

•
Instrumentations: Data collection, oscilloscopes,
signal generators, signal analyzers, power supplies.

•
Industrial: Elevator controls, surveillance systems,
robots.

•
Home: Dishwashers, microwave ovens, VCRs,
televisions, stereos, fire/security alarm systems,
lawn sprinkler controls, thermostats, cameras, clock
radios, answering machines.

•
Printers, scanners, keyboards, displays,
modems,
hard disk drives, CD
-
ROM drives.

Embedded Rocks!

•
Embedded processors account for 100% of
worldwide microprocessor production!

•
Embedded:desktop = 100:1

•
Embedded Systems is a big, fast growing industry




$ 40 billions in 2000




$92.0 billion in 2008




$112.5 billion (estimated) by the end of 2013

•
Embedded hardware

was worth $89.8 billion in
2008 and is expected to reach $109.6 billion in
2013

•
Embedded software

generated $2.2 billion in
2008. This should increase to $2.9 billion in 2013

•
Microprocessors/Microcontrollers
are the

core
of embedded systems.

http://www.bccresearch.com/report/embedded
-
systems
-
technologies
-
markets
-
ift016c.html


Computer Technology


Dramatic Change

•
Processor

–
2X in speed every 1.5 years;

100X performance in last decade

•
Memory

–
DRAM capacity: 2X / 2 years;
64X size in last
decade

–
Cost per bit: improves about 25% per year

•
Disk

–
capacity: > 2X in size every 1.0 years

–
Cost per bit: improves about 100% per year

–
250X size in last decade

Computer Technology


Dramatic Change!

•
State
-
of
-
the
-
art PC (at least…)


–
Processor clock speed:

5000
Mega
Hertz


(5.0
Giga
Hertz)

–
Memory capacity:

4000
Mega
Bytes


(4.0
Giga
Bytes)

–
Disk capacity:

2000
Giga
Bytes


(2.0
Tera
Bytes)

–
New units!
Mega

=>
Giga
,
Giga

=>
Tera

(Kilo, Mega,
Giga
,
Tera
,
Peta
,
Exa
,
Zetta
,
Yotta = 10
24
)

Kilo, Mega, etc. are incorrect Terminologies!

Microprocessors

are everywhere

in our life.

Microcontroller Components
–

Memory

•
Each memory location has
a specific address

•
We must supply an address
to access the corresponding
location

•
R/W allows us to select
reading or writing

•
Various types of memory
for different functions and
speeds

Memory location 0

Memory location 1

Memory location n
-
1

Memory location n
-
2

address

data

r/w

Microcontroller Components
–

Memory

•
Read Only Memory
-

Memory that can only be read

–
Holds the program code for a microprocessor used in an embedded
system where the code is always the same and is executed every
time the system is switched on

–
Computer BIOS, boot
-
up information

•
Other types of Read Only Memory

–
Erasable Programmable Read Only Memory (EPROM)
–

Similar
to ROM but can be erased (exposure to ultraviolet light) and
reprogrammed

–
Electrically Erasable Programmable Read Only Memory
(EEPROM)
–

more common that EPROM because it can be erased
by the microprocessor

–
Flash Memory, Ferroelectric RAM (FRAM), Magnetic Random
Access Memory (MRAM)

Microcontroller Components
–

Memory

•
Random Access Memory
–

used to store dynamic data when processor
is running

–
Holds program code and data during execution

–
Can be accesses in any random order
–

unlike takes or disks

•
Some types of RAM

–
Static RAM (SRAM)
–

Uses transistors to store bits, fast SRAM is used
for cache

–
Dynamic RAM (DRAM)
–

Uses capacitors to store bits, must be
refreshed, smaller and cheaper than SRAM

•
Fast Page Mode (FPM), Extended Data Out (EDO)

•
Synchrounous DRAM (SDRAM)
–

introduced in 1997 and replaced most
DRAM in computers by 2000

•
Double Data Rate (DDR SDRAM)
–

uses both clock edges found today in
most computers

•
Direct Rambus DRAM (RDRAM)
–

somewhat of a flop

Microcontroller Components
–

CPU

•
Smart part

–
Processes instructions and data

–
All the parts of a microprocessor

•
Registers
–

fast memory used to
store operands and other
information

–
Condition register
–

positive/negative result

–
Exception register
–

overflow
condition

–
Loop count register

•
Load
-
store architecture

Register 0

Register 1

Register n
-
1

data

address

r/w

CPU

ALU

inst

Microcontroller Components
–

I/O

•
Connection to the outside world

•
Examples

–
Analog to Digital Converter

–
Temperature Sensor

–
Display

–
Communications Circuit

Microcontroller Components
–

BUS

•
Group of wires used to transport information

•
CPU to Memory

–
Address bus

–
Data bus

•
CPU to I/O

–
Port mapped I/O
–

used when address space is limited,
special instructions are needed for I/O

–
Memory mapped I/O
–

I/O looks like memory
locations, easier to use and common in Reduced
Instruction Set Computing (RISC)

MPU
-
Based Systems

•
System hardware

–
Discrete components

•
Microprocessor, Memory, and I/O

–
Components connected by buses

•
Address, Data, and Control

•
System software

–
A group of programs that monitors the
functions of the entire system

MPU
-
Based Time

and Temperature System

MCU
-
Based Systems

•
Includes microprocessor, memory, I/O
ports, and support devices (such as timers)
on a single semiconductor chip

•
Buses are generally not available to a
system designer

•
I/O ports are generally multiplexed and can
be programmed to perform different
functions

MCU
-
Based Time

and Temperature System

Read
--

Computer Architectures

•
Princeton versus Harvard Architecture

•
CISC versus RISC processors

•
Microprocessors and Microcontrollers

Processor Performance


CPU Time



= # Cycles
×

Cycle Time



= # Instructions
×

CPI
×

Cycle Time


CPI: Cycles per instruction

Embedded System Programming

•
Key factors in embedded programming

–
Speed
–

timing constraints, limited processing power

–
Code size
–

limited memory, power

•
Programming methods

–
Machine Code
–

bits

–
Low level language
–

assembly

–
High level language
–

C, C++, Java

–
Application level language
–

Visual Basic, Access

•
Levels of abstraction
–

factor out details to focus
on few concepts at a time

Embedded System Programming

•
Why use C in embedded programming?

–
Ease of management of large embedded projects

–
Provides an additional level above assembly
programming

–
Fairly efficient

–
Supports access to I/O

•
Why use assembly?

–
High speed, low code size

–
However, difficult to do a large project in assembly

•
From various sources