Cấu trúc máy tính - Bài 7 Bộ định thời 8253 docx

bµi 7
Bé ®Þnh thêi
8253



      

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()%*+,-!.
/0
123)45+&ì6%78%
9

1. Giíi thiÖu
RESET
tíi 8088
OSC

14,3818 Mhz
®Õn khe c¾m
më réng

PCLK
2,38683 Mhz
tíi 8253
CLK

4,772776 Mhz
tíi 8088


READY
tíi 8088
510 Ω

510 Ω

X
1

X
2

XTAL
OSC
14,31818
Mhz
D
Q
CK
Chia 2

SYNC
CK
D Q
FF2
Chia 3

SYNC
CK

D Q
FF2
F/
EFI
CSYNC
RDY1
RDY2
NC




/WAIT
:;2"$%<%<
=
RES
C
DMAWAIT
RDY
ASYNC
AEN2
AEN1


&%"!"-!./>%?
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<%<<%9
%"A'B"C"!""+
-") DE


F3)<%<"'B
7@%"9$G4HI$1
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 !"#9%4-
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
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
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"+

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
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'>?J%/"


2. Bé ®Þnh thêi
8253
OP"6")
#-I
#-
#-
QIRQS
Q''
TQ

UT
=I
=
V
EV7W49
X-7W
4
XY"%
4Z%"
'%
,
[\I
'KI
]I
[\
'K
]
[\
'K
]
:;^VJ<)9
=

1
2
3
4
5
6
7

8
9
10
11
12
8
2
5
3
Vcc
A1
A0
CLK2
OUT2
GATE2
CLK1
GATE1
OUT1
D7
D6
D5
D4
D3
D2
D1
D0
CLK0
OUT0
GATE 0
GND

D7-D0
A0
A1
8253
CLK0
GATE0
OUT0
CLK1
GATE1
OUT1
CLK2
GATE2
OUT2
)&/"N

WR
RD
CS
WR
RD
CS
24
23
22
21
20
19
18
17
16

15
14
13

C%^X'"_
"P%"A',
V==I P%
III #-I
II #-
II #-
I '%

$$ \Z%"Y
,

:;,
QSQ1QQQQQQI

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II )9#-
I(+[V
I(+2V
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II Y9#-I
I Y9#-
I Y9#-
\Z%`+4
Y"#
III27KI

II27K
$I27K
$27K
II27K
I27K
I#-+N
 Qa7K"'7K3b
3. tõ ®iÒu khiÓn vµ Khëi t¹o
8253

QIc"Y#-

(+NaIRdddd:b'.

 QaIR^^^^:b

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
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
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Q>Q>Qc Y"#
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27KI $%#-#
27K $%9g%+F"6%
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27K $%/"+!9g%
+F
--
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+F
"6%

QQc"Y9.K+3)
#-

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
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"'
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(+9.K&Y%3)B+a[Vb
(+[V&?"2V3'

B"C"!"9#-#-
4@

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
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II )9#-
I(+[V
I(+2V
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II Y9#-I
I Y9#-
I Y9#-
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Y"#
III27KI
II27K
$I27K
$27K
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I27K
I#-+N
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tõ ®iÒu khiÓn vµ Khëi t¹o 8253

i/78
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'b;-'"_"P%%!"
,
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$%Z%F3)&'I\:k#

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>2:k,I\:kjII,IjI
\jIn13G78%[V
mX\jIIIIIj:

?J%&;
2]i=[>:
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2]i=[>I
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
cIIIj1:
?J%&;?3'c
2]i=[>1:
]E^S:>=[
2]i=0>II
]E^1:>=[
2]i=[>=:
]E^1:>=[

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27K $%9g%+F"6%
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27K $%/"+!9g%
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27K $%/"+!9g%
+F
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

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i/78c27KI
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(jIII0!"/&']E
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"'$)%B+


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4L"'>&%$%($
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(jII27K
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$%<%<>=o?`"/"+!
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4L
IIµ3
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1II
µ3
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UT

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3'9#-?`"+>
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
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
27K fL%Y\/"+!"6%


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%s!&;4e+4

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/&']E# ]E(?`"45+
&;"#
Cc

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9#-#+8"&']E
µ3µ3µ3
SIµ3((
=oj
]E
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