EE3248
Microprocessor & Microcontroller
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Chapter 1 - Microprocessor Basics
Basic microprocessor system:
–
–
the CPU, memory,
I/O, and buses subsystems
Basic operation of microprocessor system:
fetch & execute cycle,
–
–
–
the architecture of microprocessors & microcontrollers,
some typical 8-bit microcontrollers and their features,
memory read and write operations.
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EE3248
Microcontroller and Microprocessor Systems
Revision
Bit:
Basic unit of information in computer that stands for “binary
digit,” with the values 0 or 1 (low or high) only.
Byte:
A group of 8 bits.
Nibble: A group of 4 bits (half a byte).
Processor word length:
The size of the group of bits a processor
is designed to use as a single unit or word. E.g. 8-bit, 16-bit, or
32-bit computer.
Most Significant Bit (MSB) & Least Significant Bit (LSB):
E.g. For an 8-bit binary number:
1
MSB
0
0
1
0
1
1
0
3LSB
Review of Number Systems:
Decimal to Binary & vice versa
Hexadecimal to Binary & vice versa
Octal to Binary & vice versa
E.g.
Convert 8210 to binary
8210 = 10100102
Convert 111001112 to decimal
111001112 = 23110
Convert F116 to binary
F116 = 100100012
Alphanumeric Codes:
Alphabets (A, B, C, …), Numbers (1,2,3,…), and characters ( $, *,%,@…)
are represented by a unique binary code.
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ASCII code:
(American Standard Code for Information Interchange)
 A character is represented by a 7 bit binary number
(X6…X0)
A  100 00012 = 41H
a  110 00012 = 61H
E.g.
BCD code: Binary-Coded Decimal
 Each decimal digit is represented by its' 4-bit binary
equivalent.
E.g.
9810 = 0110 00102 = 1001 1000BCD
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1’s and 2’s Complement number:
 For a negative number, -A:
1's complement = A'
2’s complement = A' + 1
Eg. Find the 2’s complement number for a 4-bit system
X = 710 = 01112
X’= -710 = 10002
2’s complement  X’+ 1 =
10012
 Range of an N-bit 2’s complement number, X:
-2N-1  X  2N-1 - 1
What is the range of an 8-bit 2’s complement number?
-128  X  +127
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.
Combinational Logic Circuit
Output is decided by current input only
Basic logic gates: Inverter, AND, OR, NAND, NOR, XOR
E.g. Adder, decoder, multiplexer and etc.
OR
A
0
0
1
1
B
0
1
0
1
AND
Y
A
0
0
1
1
B
0
1
0
1
NOR
Y
A
0
0
1
1
B
0
1
0
1
NAND
Y
A
0
0
1
1
B
0
1
0
1
XOR
Y
A
0
0
1
1
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B
0
1
0
1
Y
Arithmetic Operation
Addition:
• The sum of a binary number and its 2’s complement is zero
E.g. Consider 4510 is added to its 2’s complement
counterpart in an 8-bit system:
auxiliary carry
1
0
carry out + 1
1 0
1
0
1
0
1
1
0
0
1
0
1
0
1
1
0
0
1
1
0
0
1
0 1 [45]
1 1 [-45]
0 0
8-bit results
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Subtraction:
Borrow
1
1
0 1 0 0
- 0 1 1 0
1 1 1 0
1 1 0 1 [77]
0 1 0 0 [100]
1 0 0 1 [-23]
Results in 8-bit 2's
complement
Multiplication:
x
0
1 1
0 0 0
0 1 0 0
1
0
1
0
0
0
0
1
1
1
0
1
0 1
0 1
0 1
0
0 0 1
Multiplicand
Multiplier
[13]
[5]
Partial
product
[65]
Product
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Division:
[4] Divisor
0 1 0 0
0 0 1 0
0 1 0
0
Partial
0
remainder
1
1
0
1
1
0
0
0 1 1
1 0 1
1
0
1
1
0
0
0 1
0 0
1
Quotient
Dividend
[11]
[45]
Remainder
Overflow:
- Consider the addition of two 8-bit 2’s complement numbers
0 1 0 0
+ 0 1 1 0
1 0 1 1
1 1 0 1
[77]
0 1 0 0 [100]
0 0 0 1 [-79!?]
An error has occurred as the results is outside the range
-128  X  127
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Parity: number of ‘1’
Even parity:
Set the parity bit to 1 or 0 to make the total number of ‘ones’ even
Odd parity:
Set the parity bit to 1 or 0 to make the total number of ‘ones’ odd
Even parity 0
0 1 0 0 1 1 0 1
Odd parity
0 1 0 0 1 1 0 1
1
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Example:
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What is a system?
Interconnection of components to perform
specified functions is referred to as a system.
If all the components are digital in nature, it is
called a digital system.
What is a computer system?
A set of software and interconnected hardware
which processes data in a meaningful way.
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What is Computer ?
Computer
Automatic data processing
Data Storage & retrieval
Hardware - equipment
Software - programs
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Major Components of a Computer
Mass storage,
HID(human interface
device:keyboard,
mouse, VDU
RAM, ROM
MEMORY
I/O
SYSTEM
BUS
Computer
Address, data and
control buses
CPU
CU, ALU,
registers
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von Neumann Architecture
Main
Memory
(Code
&
Data)
ALU
I/O
CU
CPU
*Named after the mathematician, John von Neumann
Von Neumann began the design of IAS (Institute for Advanced
Studies) computer in 1946 and completed it in 1952.
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Stored Program Computer
Input
CPU / P
Output
Memory
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What is Microprocessor ?
CPU
Control unit,
instruction decoder,
ALU, registers
Single-chip CPU
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Past Microprocessors ...
1971 - Intel 4004, 1st single chip CPU, 4-bit processor
1972 - Intel 4040, enhanced 4004, 60 instructions
1972 - Intel 8008, 8-bit P
1972 - Texas Instrument TMS 1000, 1st single C, 4-bit
1974 - Intel 8080, successor to the 8008, used in Altair 8800
1975 - Motorola 6800, used MOS technology
1976 - Intel 8085, updated 8080, +5V power supply
1976 - Zilog Z80, improved 8080
1976 - TI TMS 9900, 1st 16-bit P
1978 - Zilog Z8000, Motorola 68000, 16-bit P
1978 - Intel 8086, 16-bit, IBM’s choice...
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What is Microcontroller ?
MEMORY
I/O
SYSTEM
BUS
CPU
Single-chip microcomputer system
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Past Microcontrollers ...
1972
- Texas Instrument TMS 1000, 1st single C, 4-bit
1976
- Intel 8048, 8-bit C, 1k ROM, 64b RAM, 27 I/O
1980
- Intel 8051, 4k ROM, 128b RAM, 32 I/O, 2 16-bits timers
1980s - MCS-51 family
- Other Cs




Intel 8031, 8052, 8751, …
Atmel AT89C51, AT 89C1052/2051,…
Dallas Semiconductor DS5000 series…
Philips, National Semiconductor, ...



Microchip PIC16 series
Motorola 68HC11
Zilog’s Z86
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General Structure of a C
I/O
Interrupt
Control
CPU
Serial
Interface
Parallel
Interface
Internal address, data, & control buses
Timers/
Counters
RAM
ROM
Memory
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Microprocessor System
vs
Microcontroller System
Data Bus
CPU
RAM
ROM
I/O
Port
Timer
Serial
COM
Port
CPU
RAM
I/O
Port
Timer
ROM
Serial
COM
Port
Address Bus
General-Purpose Microprocessor System
Microcontroller
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Example of a Microprocessor system
CPU Motorola 6802
EPROM
2732
I/O chip
6821
http://www.sbprojects.com/projects/nano6802/nano6802.htm
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Example of a Microprocessor system
CPU
I/O
EPROM
http://www.sbprojects.com/projects/nano6802/nano6802.htm
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Example of a Microcontroller system
http://www.ozitronics.com/robotics.html
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Microprocessor System Vs Microcontroller System
P

Hardware 
Architecture 


Application



Instruction
set



Cost

Single-chip CPU
RAM-ROM ratio high
Interrupt, I/O, Timer – external.
Higher performance (+2GHz)
Not much on Real-time
Microcomputer system
Processing information
C







Process intensive to handle

large volume of data
Operates on byte, words,

pointers, and arrays.

Longer development time

ANDing, ORing, XORing in
bit level is less easy
Expensive (Celeron 2000MHz 
~RM250)
Single-chip computer
ROM-RAM ration high
Interrupt, I/O, timer-Internal
Less performance (<80MHz)
Need to respond to Real time
Control– oriented activities
Control of I/O devices
Control intensive to handle I/O
using single Bit
Operates mostly on Bit & byte
Shorter development time
ANDing, ORing, XORing in
bit level is easy
Cheap(AT89S51 ~RM10 )
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Applications of uC / uP systems
•
•
•
•
•
•
•
•
•
•
•
•
Automobiles
Home security systems
Televisions,
DVD players
Modems,
Handphones
Smartcards
Digital clock
Washing machines
Microwaves ovens,
Air Conditioners,
etc
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Major 8-bit Microcontrollers
• Intel 8051
• Motorola 68HC11
• Microchip PIC16XX
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Intel 8051
 Power Control Modes
 4KBytes On-Chip ROM / EPROM
 128 x 8-bit RAM
 32 Programmable I / O Lines
 Two 16- Bit Timers / Counters  5 Interrupt Sources
 Boolean Processor
 TTL & CMOS Compatible Logic
 64KBytes External Program
Memory Space
 64KBytes External Data Memory
Space
 Full Duplex UART
 Available in 12MHz & 16MHz
Versions
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INT1
INT0
Timer 1
Timer 0
Serial Port
Interrupt
control
Intel 8051
T1
T0
Other
registers
Timer 1
RAM
128 bytes
Timer 0
CPU
Oscillator
Bus control
EA
RST
I/O Ports
Serial port
ALE
PSE
TxD*
P0
A/D
P1
P2
P3
A/D
RxD*
* Alternate pin assignment
for P3
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Motorola MC68HC11
 256 bytes of on-chip RAM
 512 bytes of on-chip EEPROM
 4-channel 8-bit analogue-to-
 16-bit timer system
digital converter
 Asynchronous serial
communication interface
 Real-time interrupt circuit
 Synchronous serial peripheral
interface
 Power saving STOP and WAIT
modes
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Motorola MC68HC11
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Microchip PIC16C64
 RISC architecture (35 single
 In-circuit serial programming
word instruction)
 128 bytes RAM, 2Kbytes
EPROM
 3 Timer/Counters, 1 watchdog
timer, 8 interrupt sources, 33 I/O
pins
 1 Capture/Compare/PWM
module
 Synchronous serial port (SSP)
with SPI, I2C
 Power saving SLEEP mode
 Universal synchronousasynchronous receiver transmitter
(USART/SCI)
 Programmable code
protection
 8-bit Parallel slave port (PSP)
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Microchip PIC16C64
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General features of a microcontroller
• On-chip RAM (data) and ROM (program)
• Support external program and data memory
• I/O ports for direct interfacing with other digital devices
• On-chip timer/counter
• Parallel and serial communication capabilities
• Interrupt from external stimuli
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Choosing the right microcontroller
Critical decisions in a project:

I/O requirement:
 Number of general purpose I/O ports/pins
 Special interfaces (UART, A/D, D/A)

Size of RAM and ROM (type of ROM)

On-chip peripherals (timers, counters)

Speed requirement

Cost

Availability (now and future)

Development support:
 Assembler, compiler, linker
 Debugging tools
 Support from manufacturer and users (forums)
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