8051 chap1 introduction VI XỬ LÝ

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The 8051 Microcontroller

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Ref. I. Scott Mackenzie, The 8051 Microcontroller

Instructor
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Faculty of Electrical and Electronics Engineering
Ho Chi Minh City University of Technology (HCMUT)
Trường Đại Học Bách Khoa - ĐHQG TP.HCM
Email: ;
Website: sites.google.com/site/chithong

Ref. I. Scott Mackenzie

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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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Grading
• Quizzes and homework assignments: 20%
– Homework is due at the beginning of class

• Mid-term: 30%
• Final: 50%

Ref. I. Scott Mackenzie

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Textbooks
• The 8051 Microcontroller, 2nd Edition, I. Scott
MacKenzie, Prentice-Hall, 1995
• The 8051 Microcontroller: Architecture, Programming,
and Applications, Kenneth J. Ayala, 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
perform a specific task orLê Chítasks
Ref. I. Scott Mackenzie
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Microprocessors
• Integrated ALU and CU
• No RAM, ROM, I/O on CPU chip itself
• Example: Intel’s x86, Motorola’s 680x0

Control Unit
(CU)

Arithmetic
Logical Unit (ALU)

Central Processing Unit (CPU)

CPU
GeneralPurpose
Microprocessor

Many chips on mother’s board

Data Bus

RAM

ROM

I/O
Port

Timer

Serial
Port

Address Bus

General-Purpose Microprocessor
System
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FIGURE 1–2

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Block diagram of a microcomputer system

Architecture of computers

Ref. I. Scott Mackenzie

FIGURE 1–3

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The central processing unit (CPU)

Architecture of CPU

PCProgram counter

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FIGURE 1–4

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Bus activity for an opcode fetch cycle

Opcode fetch, decode, execution

Ref. I. Scott Mackenzie

FIGURE 1–5

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Levels of software

Shell, GUI – user
- hardware

Utilities

Booster loader,
BIOS

Keyboard, monitor
Other hardwires

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FIGURE 1–6

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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

I/O
Port

Serial
Timer COM
Port

Microcontroller

Ref. I. Scott Mackenzie

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A single chip

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Microcontroller Architectures
Memory

Address Bus
CPU

0

Program
+ Data

Data Bus
2n

Von Neumann
Architecture

Memory

Address Bus

0

Fetch Bus

CPU

Program

Address Bus 0
Data Bus
Ref. I. Scott Mackenzie

Harvard
Architecture

Data
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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

Output interfaces

Sensor conditioning

sensor

Microcontroller
(uC)

actuator

indicator

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:
An - 1An - 2 … A1A0 . A- 1 A- 2 … A- m + 1 A- m
in which 0 < Ai < r and . is the radix point.
• The string of digits represents the power series:

(∑

i=n-1

(Number)r

=

j=-1

) (∑

i

Ai r +

i=0

j=-m

(Integer Portion)
Ref. I. Scott Mackenzie

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)

Aj r j

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+

(Fraction Portion)
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Representation of Number Systems
General
Radix (Base)
Digits
0
1
2
3
Powers of 4
Radix
5
-1
-2
-3
-4
-5

Decimal

Binary

r

10

2

0 => r - 1

0 => 9

0 => 1

r0
r1
r2
r3
r4
r5
r -1
r -2
r -3
r -4
r -5

1
10
100
1000
10,000
100,000
0.1
0.01
0.001

0.0001
0.00001

1
2
4
8
16
32
0.5
0.25
0.125
0.0625
0.03125

Ref. I. Scott Mackenzie

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Decimal (Radix r = 10)
4

0

7

.

6

2

5

102

101

100

.

10-1

10-2

10-3

4x102

0x101

7x100

.

6x10-1

2x10-2

5x10-3

400

0

7

.

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

1

22

21

20

.

2-1

2-2

2-3

1x22

0x21

1x20

.

0x2-1

1x2-2

1x2-3

4

0

1

.

0

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
0
1
2
3
4
5
6
7

Binary

0
1
2
3
4
5
6
7

Hexadecimal Decimal

0000
0001
0010
0011

0100
0101
0110
0111

8
9
A
B
C
D
E
F

Binary

8
9
10
11
12
13
14
15

1000
1001
1010
1011
1100

1101
1110
1111

5

A

0

.

4

D

1

162

161

160

.

16-1

16-2

16-3

5x162

10x161

0x160

.

4x16-1

13x16-2

1x16-3

1280

160

0

.

0.25

0.0508

0.0002

5A0.4D1
H = 1280 + 160 + 0 +Lê0.25
+ 0.0508 + 0.0002 = 1440.301
Ref. I. Scott Mackenzie
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Converting decimal to binary
8 . 625 D = ? B
8
4
2
1

:2 =
:2 =
:2 =
:2=

4 remainder
2 remainder
1 remainder
0 remainder

0
0
0
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
1480.4296875D=?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 10 B
3

B

5

D

.

.

E

6

A

H

Converting binary to octal

2

C

9

8

H

0 01011001001.11101000 B
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BCD (Binary Coded Decimal)
Decimal
0
1

2
3
4
5
6
7
8
9

BCD
(8 4 2 1)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001

Ref. I. Scott Mackenzie

Ex:

12 = 0001 0010 (BCD)
39 = 0011 1001 (BCD)

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ASCII Code
b6 b5 b4
b3b2b1b0 Hex
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1 1 Mackenzie
10
Ref. I. Scott
1111

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0
1
2

3
4
5
6
7
8
9
A
B
C
D
E
F

000

001

010

011

100

101

110

111

0

1

2

3

4

5

6

7

NUL
SOH
STX
ETX
EOT
ENQ
ACK
BEL
BS
HT
LF
VT
FF
CR

SO
SI

DLE
DC1
DC2
DC3
DC4
NAK
SYN
ETB
CAN
EM
SUB
ESC
FS
GS
RS
US

SP
0
!
1
”
2
#
3
$
4

%
5
&
6
’
7
(
8
)
9
*
:
+
;
,
<
=
Lê. Chí Thơng >
/
?

@
A
B
C
D
E
F
G
H

I
J
K
L
M
N
O

P
Q
R
S
T
U
V
W
X
Y
Z
[
\
]
^
_

`
a
b
c
d

e
f
g
h
i
j
k
l
m
n
o

p
q
r
s
t
u
v
w
x
y
z
{
|
}
~ 26
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Boolean (Logical) Operations
a

NOT a

a

b

a AND b

0

1

0

0

0

1

0

0

1

0

1

0

0

1

1

1

a

b

a OR b

a

b

a XOR b

0

0

0

0

0

0

0

1

1

0

1

1

1

0

1

1

0

1

1

1

1

1

1

0

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)

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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
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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
component that allows
the storage and retrieval
of data
• Main memory is usually
called RAM
• Memory is usually
organized as a table of
Addresses
bytes or words

are usually
shown in
hexadecimal

Ref. I. Scott Mackenzie

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0000
0001
0002
0003
0004
0005

3F
2C
41
FF
00
1E
Data values
are usually
bytes
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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

Ref. I. Scott Mackenzie

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ROM

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References
• I. Scott Mackenzie, The 8051 Microcontroller
• Nguyễn Trọng Luật, Bài giảng Kỹ Thuật Số
• Các tài liệu trên Internet khơng trích dẫn hoặc khơng ghi tác
giả

Ref. I. Scott Mackenzie

sites.google.com/site/chithong

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