Bài giảng Microprocessing Systems - Chapter 1: Introduction to Microcontrollers

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Microprocessing Systems

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Ref. I. Scott Mackenzie, The 8051 Microcontroller

Objectives

• Introduction fundamentals and applications of

microprocessors and microcomputers.

• Architecture, the instruction set, and applications of

8051 microcontroller family

• Basic applications of microprocessors, such as

input/output, analog-digital conversion (ADC), and

digital-analog conversion (DAC), and data acquisition.

Ref. I. Scott Mackenzie

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Textbooks

• I. Scott MacKenzie, ”The 8051 Microcontroller”, 2nd

Edition, Prentice-Hall, 1995

• Kenneth J. Ayala, “The 8051 Microcontroller:

Architecture, Programming, and Applications”, West

Publishing Company

Ref. I. Scott Mackenzie

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Chapter 1

Introduction to Microcontrollers

Ref. I. Scott Mackenzie

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These are …

embedded systems

An embedded system is a system in which a

processor/microcontroller/computer is embedded to

_Rp_ef.e_{I. S}r_cof_tto_Mr_acm_kenziea specific task or tasks

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Microprocessors

Control Unit

• Integrated ALU and CU

(CU)

• No RAM, ROM, I/O on CPU chip itself

• Example: Intel’s x86, Motorola’s 680x0

Arithmetic

Logical Unit (ALU)

Central Processing Unit (CPU)

Many chips on mother’s board

Data Bus

RAM

CPU

General-

Purpose

Micro-

Serial

Port

I/O

Port

ROM

Timer

processor

Address Bus

General-Purpose Microprocessor System

Ref. I. Scott Mackenzie

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FIGURE 1–2

Block diagram of a microcomputer system

Architecture of computers

Ref. I. Scott Mackenzie

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FIGURE 1–3

The central processing unit (CPU)

Architecture of CPU

PC-

Program counter

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FIGURE 1–4

Bus activity for an opcode fetch cycle

Opcode fetch, decode, execution

Ref. I. Scott Mackenzie

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FIGURE 1–5

Levels of software

Shell, GUI – user

- hardware

Utilities

Booster loader,

BIOS

Keyboard, monitor

Other hardwires

Ref. I. Scott Mackenzie

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FIGURE 1–6

Detailed block diagram of a microcomputer system

Ref. I. Scott Mackenzie

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Microcontrollers

• Integrates CPU, RAM, ROM, I/O ports, … on a

single chip

• Sometimes called a "computer on a chip"

• Typically used in embedded applications

• Example: Motorola’s 6811, Intel’s 8051, Zilog’s Z8

and PIC 16X

CPU RAM ROM

A single chip

Serial

I/O

Port

Timer

COM

Port

Microcontroller

Ref. I. Scott Mackenzie

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Microcontroller Architectures

Memory

0

Address Bus

Program

+ Data

Von Neumann

Data Bus

CPU

Architecture

2ⁿ

Memory

0

Address Bus

Program

Fetch Bus

Harvard

Architecture

0

Address Bus

Data Bus

Data

Ref. I. Scott Mackenzie

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Embedded System

• Embedded system: the processor is embedded into

that application.

• An embedded product usually uses a microcontroller

to do one task only.

• In an embedded system, there is only one application

software that is typically burned into ROM

Ref. I. Scott Mackenzie

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Embedded System

sensor

actuator

indicator

Microcontroller

(uC)

sensor

Ref. I. Scott Mackenzie

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Representation of Number Systems

• Positive radix, positional number systems

• A number with radix r is represented by a string of

digits:

A_{n - 1}A_{n - 2}… A₁A₀. A_{- 1}A_{- 2}… A_{- m + 1}A_{- m}

in which 0 < A_i< r and . is the radix point.

• The string of digits represents the power series:

j = - 1

i = n - 1

=

i

j

(Number)r

( )₊( )

A r



i

j

i = 0

j = - m

+

(Integer Portion) (Fraction Portion)

Ref. I. Scott Mackenzie

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Representation of Number Systems

General

r

Decimal

10

Binary

2

Radix (Base)

Digits

0 => r - 1

0 => 9

0 => 1

0

1

2

3

4

5

r⁰

r¹

r²

r³

r⁴

1

2

10

100

4

1000

10,000

100,000

0.1

8

Powers of

Radix

16

r⁵

32

-1

-2

-3

-4

-5

r ^-1

r ^-2

r ^-3

r ^-4

r ^-5

0.5

0.01

0.25

0.125

0.0625

0.03125

0.001

0.0001

0.00001

Ref. I. Scott Mackenzie

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Decimal (Radix r = 10)

4

0

7

.

6

2

5

10²

4x10²

400

10¹

0x10¹

0

10⁰

7x10⁰

7

.

10^-1

10^-2

10^-3

6x10^-12x10^-25x10^-3

0.6 0.02 0.005

400 + 0 + 7 + 0.6 + 0.02 + 0.005 = 407.625

Binary (Radix r = 2)

1

0

1

.

0

1

2²

1x2²

4

2¹

0x2¹

0

2⁰

1x2⁰

1

.

2^-1

0x2^-1

0

2^-2

2^-3

1x2^-2

1x2^-3

0.25

0.125

101.011 B = 4 + 0 + 1 + 0 + 0.25 + 0.125 = 5.375

Ref. I. Scott Mackenzie

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Hexadecimal or Hex (Radix r = 16)

Hexadecimal Decimal Binary

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0000

0001

0010

0011

0100

0101

0110

0111

8

9

8

9

1000

1001

1010

1011

1100

1101

1110

1111

A

B

C

D

E

F

10

11

12

13

14

15

5

A

0

.

4

D

1

16²

5x16²10x16¹0x16⁰

1280 160

16¹

16⁰

.

16^-1

16^-2

16^-3

4x16^-113x16^-21x16^-3

0

0.25 0.0508 0.0002

5A0.4D1 H = 1280 + 160 + 0 + 0.25 + 0.0508 + 0.0002 = 1440.301

Ref. I. Scott Mackenzie

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Converting decimal to binary

8 . 625 D = ? B

8 : 2 = 4 remainder 0

4 : 2 = 2 remainder 0

2 : 2 = 1 remainder 0

1 : 2 = 0 remainder 1

1 0 0 0 . 1 0 1 B

0.625 x 2 = 1.25 save the integer digit 1

0.25 x 2 = 0.5 save the integer digit 0

0.5

x 2 = 1.0 save the integer digit 1

Ref. I. Scott Mackenzie

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Converting decimal to hex

1 4 8 0 . 4 2 9 6 8 7 5 D = ? H

1480 : 16 = 92 remainder 8

92 : 16 = 5 remainder 12

5 : 16 = 0 remainder 5

5 C 8 . 6 E H

0.4296875 x 16 = 6.875 save the integer digit 6

0.875

x 16 = 14.0 save the integer digit 14

Ref. I. Scott Mackenzie

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Converting binary to hex

0 0

1 1 1 0 1 1 0 1 0 1 1 1 0 1 . 0 1 1 0 1 0 1 B

0

3

B

5

D .

6

A

H

Converting binary to octal

2

C

9 .

E

8

H

0 0 1 0 1 1 0 0 1 0 0 1 . 1 1 1 0 1 0 0 0 B

Ref. I. Scott Mackenzie

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BCD (Binary Coded Decimal)

Decimal

BCD

(8 4 2 1)

0

1

2

3

4

5

6

7

8

9

0 0 0 0

0 0 0 1

0 0 1 0

0 0 1 1

0 1 0 0

0 1 0 1

0 1 1 0

0 1 1 1

1 0 0 0

1 0 0 1

Ex: 12 = 0001 0010 (BCD)

39 = 0011 1001 (BCD)

Ref. I. Scott Mackenzie

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ASCII Code

b₆b₅b₄

0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

b₃b₂b₁b₀Hex

0

1

2

3

4

5

6

7

0 0 0 0

0 0 0 1

0 0 1 0

0 0 1 1

0 1 0 0

0 1 0 1

0 1 1 0

0 1 1 1

1 0 0 0

1 0 0 1

1 0 1 0

1 0 1 1

1 1 0 0

1 1 0 1

0

1

NUL DLE SP

0

1

2

3

4

5

6

7

8

9

:

@

A

B

C

D

E

F

P

Q

R

S

`

a

b

c

d

e

f

g

h

i

j

k

l

m

n

o

p

SOH DC1

STX DC2

ETX DC3

EOT DC4

ENQ NAK

ACK SYN

BEL ETB

BS CAN

!

”

#

$

%

&

’

q

2

r

3

s

4

T

U

V

W

X

Y

Z

[

t

5

u

6

v

7

G

H

I

w

8

(

x

9

HT

LF

EM

)

y

A

B

C

D

E

F

SUB

VT ESC

*

+

,

J

z

;

K

L

M

N

O

{

FF

CR

SO

SI

FS

GS

RS

US

<

=

>

?

\

|

-

]

}

1 1 1 0

.

^

~

Ref. I. Scott Mackenzie

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1 1 1 1

/

_

DEL ²⁴

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Boolean (Logical) Operations

a

0

1

NOT a

a

0

1

b

0

1

0

1

a AND b

0

1

0

a

b

a XOR b

a

b

0

1

0

1

a OR b

0

1

0

1

0

1

0

1

0

1

0

1

Ref. I. Scott Mackenzie

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Applying Boolean Operations

• Force a bit or bits to zero

– Sometimes called "masking out bits"

• Use a "mask" byte with

– 0's in positions to be cleared (forced to 0)

– 1's in positions to be unchanged

• Perform an AND with the mask

– x AND 0 = 0 (domination)

– x AND 1 = x (identity)

Ref. I. Scott Mackenzie

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Applying Boolean Operations

• Force a bit or bits to one

– Sometimes called "setting bits"

• Use a "mask" byte with

– 1's in positions to be set (forced to 1)

– 0's in positions to be unchanged

• Perform an OR with the mask

– x OR 0 = x (identity)

– x OR 1 = 1 (domination)

Ref. I. Scott Mackenzie

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Applying Boolean Operations

• Toggle a bit or bits

– Sometimes called "flipping or complementing

bits"

• Use a "mask" byte with

– 1's in positions to be toggled (complemented)

– 0's in positions to be unchanged

• Perform an XOR with the mask

– x XOR 0 = x (identity)

– x XOR 1 = NOT x

Ref. I. Scott Mackenzie

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Combining Bits in Separate Bytes

• Bit patterns from two bytes are to be combined

– The important bits of each byte must be aligned with 0 (and

unimportant) bits in the other byte

• The OR of the two bytes, combines them into one

– The bold bits are the important ones:

00110000

OR 00001010

00111010

Ref. I. Scott Mackenzie

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Shifting

• Move bits in a byte to the left or right

– 11011100 shifted left is 10111000

– 11011100 shifted right is 01101110

• In these examples, a zero (0) was brought in to

fill the vacated position

– Variations on the basic shift fill this position

differently

Ref. I. Scott Mackenzie

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Rotating

• Move bits in a byte to the left or right in a

circular pattern

– 11011100 rotated left is 10111001

– 11011100 rotated right is 01101110

• In these examples, the bit shifted out is used to

fill the vacated position

– There are some variations of this behavior as well

Ref. I. Scott Mackenzie

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Application of Shifts

• When a byte (or word) is interpreted

numerically (as a binary representation of a

number)…

– Left shift is equivalent to multiplication by 2

– Right shift is equivalent to division by 2

– 5CH shifted left becomes B8H

• 92 * 2 = 184

– 5CH shifted right is 2EH

• 92 / 2 = 46 (remainder if any is thrown away)

Ref. I. Scott Mackenzie

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Multiplication Tricks

• Every multiplication can be accomplished by

shifting and adding

– Just regroup using only multiplications by powers

of 2 and additions

• 10 * n = (8 + 2) * n

•

= 8 * n + 2 * n

– or

• 10 * n = (2 * (4 + 1)) n

•

= 2 * (4 * n + n)

Ref. I. Scott Mackenzie

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Memory

• A computer system

0000

0001

0002

0003

0004

0005

3F

2C

41

FF

00

1E

component that allows

the storage and retrieval

of data

• Main memory is usually

called RAM

• Memory is usually

organized as a table of

bytes or words

Addresses

are usually

shown in

Data values

are usually

bytes

hexadecimal

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RAM and ROM

• RAM: Random Access Memory

– Access time does not vary by address

– Read & write memory

– Typically volatile

• ROM: Read Only Memory

– Also a random access memory

– Retains data even when power is removed

Ref. I. Scott Mackenzie

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RAM and ROM

RAM

ROM

Ref. I. Scott Mackenzie

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References

• I. Scott Mackenzie, The 8051 Microcontroller

• Nguyễn Trọng Luật, Bài giảng Kỹ Thuật Số

• Các tài liệu trên Internet không trích dẫn hoặc không ghi tác

giả

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Bài giảng Microprocessing Systems - Chapter 1: Introduction to Microcontrollers - Lê Chí Thông