Microprocessor Based Systems.ppt

An Introduction to
Microprocessors and
Microcontrollers

A little History
 What is a computer?
 A programmable electronic device that can store,
retrieve, and process data.
 A machine that manipulates data according to a list of
instructions.
 Classification of Computers (power and price)
 Personal computers
 Mainframes
 Supercomputers
 Dedicated controllers – Embedded controllers

Mainframes
 Massive amounts of memory
 Use large data words…64 bits or more
 Mostly used for military defense and large business
data processing
 Examples: IBM 4381, Honeywell DPS8

Personal Computers
 Any general-purpose computer
 intended to be operated directly by an end user
 Range from small microcomputers that work with 4-bit
words to PCs working with 32-bit words or more
 They contain a processor – known by different names:
 Microprocessor – built using Very-Large-Scale
Integration technology; the entire circuit is on a single
chip
 Central Processing Unit (CPU)
 Microprocessor Unit (MPU) – similar to CPU
http://en.wikipedia.org/wiki/Personal_computer

Supercomputers
 Fastest and most powerful mainframes
 Contain multiple processors (CPUs)
 Used for scientific applications, and number crunching
 Now have teraflops performance
 FLoating Point Operations Per Second (FLOPS)
 Examples of special-purpose supercomputers:
 Belle, Deep Blue, and Hydra, for playing chess
 Reconfigurable computing machines or parts of machines
 GRAPE, for astrophysics and molecular dynamics
 Deep Crack, for breaking the DES cipher
 MDGRAPE-3, for protein structure computation
http://en.wikipedia.org/wiki/Supercomputer

Embedded Systems
 An embedded system is a special-purpose computer
system designed to perform one or a few dedicated
functions often with real-time
 An integrated device which consists of multiple devices
 Microprocessor (MPU)
 Memory
 I/O (Input/Output) ports
 Often has its own dedicated software

A little about
Microprocessor-based
Systems ……

Evolution
 First came transistors
 Integrated circuits
 SSI (Small-Scale Integration) to ULSI
 Very Large Scale Integration circuits (VLSI)
 1- Microprocessors (MPU)
 Microcomputers (with CPU being a microprocessor)
 Components: Memory, CPU, Peripherals (I/O)
 Example: Personal computers
 2- Microcontroller (MCU)
 Microcomputers (with CPU being a microprocessor)
 Many special function peripheral are integrated on a single circuit
 Types: General Purpose or Embedded System (with special functionalities)

Microprocessor-Based Systems
• Central Processing Unit (CPU)
• Memory
• Input/Output (I/O) circuitry
• Buses
– Address bus
– Data bus
– Control bus

Arithmetic
Logic
Unit
Register
Arrays
Control Unit
GP-
CPU
CLK Reg
MPU
CPU
Microprocessor-based System

Microprocessor-Based System with Buses:
Address, Data, and Control Signals

Microprocessor-based Systems
Microprocessor
 The microprocessor (MPU) is a computing and
logic device that executes binary instructions in a
sequence stored in memory.
 Characteristics:
 General purpose central processor unit (CPU)
 Binary
 Register-based
 Clock-driven
 Programmable

Microprocessor
 the “brains” of the computer
 its job is to fetch instructions, decode them, and then execute them
 8/16/32/etc –bit (how it moves the data
 contains:
ALU performs computing tasks – manipulates the data/ performs numerical and logical
computations
Registers are used for temp. storage
Control unit is used for timing and other controlling functions – contains a program
counter (next instruction’s address and status register)
System software: A group of programs that monitors the functions of the entire system

Transistors
 Vacuum Tubes: A devise to control,
modify, and amplify electric signals
 Then came transistors in 1947
 In 1960 Jack Kilby and Robert Noyce
designed the first integrated circuit (IC)
 Fairchild company manufactured logic
gates

Integrated Circuits
 Advances in
manufacturing allowed
packing more transistors
on a single chip
 Transistors and Integrated
Circuits from SSI (Small-
Scale Integration) to ULSI
 Birth of a microprocessor
and its revolutionary
impact

Microprocessors
 Noyce and Gordon Moore
started Intel
 Intel designed he first calculator
 Intel designed the first
programmable calculator
 Intel designed the first
microprocessor in 1971
 Model 4004
 4-bit; 2300 transistors, 640
bytes of memory, 108 KHz
clock speed

Memory
 Memory is a group of registers
 16 register – address: 0-15 – in binary: 0-
1111; Address lines: A0-A3
 Serves two major purposes
 storing the binary codes for the sequence of
instructions specified by programs (program)
 storing binary data that the computer needs
to execute instructions (data)

Memory Types
 R/W: Read/Write Memory; also called RAM
 It is volatile (losses information as power is removed)
 Write means the processor can store information
 Read means the processor can receive information from the
memory
 Acts like a Blackboard!
 ROM: Read-Only memory;
 It is typically non-volatile (permanent) – can be erasable
 It is similar to a Page from your textbook

Memory Classification
Expensive
Fast/
Cheap
Slow
Onetime programmable
Electronically Erasable
PROM

Erasable ROMs
 Marked Programmed ROM
 Programmed by the manufacturer
 Programmable ROM (PROM)
 Can be programmed in the field via the programmer
 Erasable Programmable ROM (EPROM)
 Uses ultraviolet light to erase (through a quartz window)
 OTP refers to one-time programmable
 Electrically Erasable Programmable ROM (EEPROM)
 Each program location can be individually erased
 Expensive
 Requires programmer
 FLASH
 Can be programmed in-circuit (in-system)
 Easy to erase (no programmer)
 Only one section can be erased/written at a time (typically 64 bytes at a time)

Input/Output (I/O) Ports
 The way the computer communicates with the
outside world devices
 Peripherals are connected to I/O ports
 Peripherals are I/O devices
 Input devices
 Output devices
 Examples
 Printers and modems,
 keyboard and mouse
 scanner
 Universal Serial Bus (USB)

Microprocessor-based
Systems - BUS
 The three components – MPU, memory, and I/O – are connected by a
group of wires called the BUS
 Address bus
 consists of 16, 20, 24, or 32 parallel signal lines (wires) - unidirectional
 these lines contain the address of the memory location to read or written
 Control bus
 consists of 4 to 10 (or more) parallel signal lines
 CPU sends signals along these lines to memory and to I/O ports
 examples: Memory Read, Memory Write, I/O Read, I/O Write
 Data bus
 consists of 8,16, or 32 parallel signal lines
 bi-directional
 only one device at a time can have its outputs enabled,
 this requires the devices to have three-state output

Expanded Microprocessor-Based System
• Note the directions
of:
• address bus
• Data bus
• Control signals
• What is the width of
the:
• address bus?
• Data bus?

 What are Microcontrollers?

First Microcontrollers
 IBM started using 8042 and 8048 (8-bit
microcontroller) in printers
 Apple Macintosh used Motorola
 1980 Intel abandoned microcontroller business
 By 1989 Microchip was a major player in designing
microcontrollers
 PIC: Peripheral Interface Controller

Embedded controllers
 Used to control smart machines
 Examples: printers, auto braking systems
 Also called microcontrollers or microcontroller units
(MCU)

Embedded controllers
Software Characteristics
 No operating systems
 Execute a single program, tailored exactly to the
controller hardware
 Assembly language (vs. High-level language)
 Not transportable, machine specific
 Programmer need to know CPU architecture
 Speed
 Program size
 Uniqueness

Microcontroller Unit (MCU)
Block Diagram
 An integrated electronic computing and logic device that
includes three major components on a single chip
 Microprocessor
 Memory
 I/O ports
 Includes support devices
 Timers
 A/D converter
 Serial I/O
 Parallel Slave Port
 All components connected by common communication lines
called the system bus.

MCU Architecture
 RISC (Harvard)
 Reduced instruction set computer
 Simple operations
 Simple addressing modes
 Longer compiled program bust faster to execute
 Uses pipelining
 CISC (Von Neuman)
 Complex instruction set computer
 More complex instructions (closer to high-level
language support)

Main 8-bit Controllers
 Microchip
 RISC architecture (reduced instruction set computer)
 Has sold over 2 billion as of 2002
 Cost effective and rich in peripherals
 Motorola
 CISC architecture
 Has hundreds of instructions
 Examples: 68HC05, 68HC08, 68HC11
 Intel
 CISC architecture
 Has hundreds of instructions
 Examples: 8051, 8052
 Many difference manufacturers: Philips, Dallas/MAXIM Semiconductor, etc.
 Atmel
 RISC architecture (reduced instruction set computer) –
 Cost effective and rich in peripherals
 AVR

Numbering system
Data format
Memory operation
System Software
(hardware/Software)
Example of a microprocessor /
microcontroller based
Let’s continue…..

Memory
 A semiconductor storage
device consisting of
registers that store
binary bits
 Two major categories
 Read/Write Memory
(R/WM)
 Read-only-Memory
(ROM)

Symbolic Representation of Memory Contents
 Addresses Registers
CODE:
READ PORT A
WRITE PORT B
STOP
What is the address bus value?
PORT A = 8000H
PORT B = 8001H
Fetch / Decode /
Execute

Software:
From Machine to High-Level Languages (1 of 3)
 Machine Language: binary instructions
 All programs are converted into the machine language
of a processor for execution
 Difficult to decipher and write
 Prone to cause many errors in writing
Machine Language
Assembly Language
High-level Language

Software: From Machine
to High-Level Languages (2 of 3)
 Assembly Language: machine instructions represented
in mnemonics
 Has one-to-one correspondence with machine
instructions
 Efficient in execution and use of memory; machine-
specific and not easy to troubleshoot
Machine Language
Assembly Language
High-level Language

Software: From Machine
to High-Level Languages (3 of 3)
 High-Level Languages (such as BASIC, C, and C++)
 Written in statements of spoken languages (such as
English)
 machine independent
 easy to write and troubleshoot
 requires large memory and less efficient in execution
Machine Language
Assembly Language
High-level Language

Data Format (8-bit) (1 of 4)
 Unsigned Integers: All eight bits (Bit0 to Bit7)
represent the magnitude of a number
 Range 0 to FF in Hex and 0 to 255 in decimal
Signed
Unsigned

 Signed Integers: Seven bits (Bit0 to Bit6)
represent the magnitude of a number.
 The eighth bit (Bit7) represents the sign of a
number. The number is positive when Bit7 is
zero and negative when Bit7 is one.
 Positive numbers: 0 to 7F (0 to 127)
 Negative numbers: 80 to FF (-1 to -128)
 All negative numbers are represented in 2’s
complement
Signed
Unsigned

 Binary Coded Decimal Numbers (BCD)
 8 bits of a number divided into groups of four, and each
group represents a decimal digit from 0 to 9
 Four-bit combinations from A through F in Hex are
invalid in BCD numbers
 Example: 0010 0101 represents the binary coding of the
decimal number 25d which is different in value from 25H.

 American Standard Code for Information Interchange
(ASCII)
 Seven-bit alphanumeric code with 128 combinations (00
to 7F)
 Represents English alphabet, decimal digits from 0 to 9,
symbols, and commands

Storing Bits in Memory
 We can store in different
memory types
 EEPROM, FLASH, RAM, etc.
 In an 8-bit RAM
 Each byte is stored in a single
memory register
 Each word is stored in two
memory locations (registers)
 DATA 0x1234
 0x12REG11 (High-order byte)
 0001 0010
 0x34REG10 (Low-order byte)
 0011 0100
What if we want to store -8?
Remember -8111 1000 (in two’s complement)

Design Examples …..
Microcontrollers vs. Microprocessors

MPU-Based Time
and Temperature System

MCU-Based Time
and Temperature System

References
 Read about microcontrollers:
http://www.mikroe.com/en/books/picbook/2_01chapter.htm
 Lots of good information exist on Wikipedia about microcontrollers
http://en.wikipedia.org/wiki/
 History of transistors:
http://inventors.about.com/library/weekly/aa061698.htm
 Nice transistor timeline by Intel:
http://www.intel.com/technology/timeline.pdf
 I used a few slides from here:
http://www.ceng.metu.edu.tr/courses/ceng336/_documents/introduct
ion.pdf

Microprocessor Based Systems.ppt

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Microprocessor Based Systems.ppt