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NHA XUAT BAN LAO DONG - XA HOI
■
HA NOI - 2004
■
-1
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LQ1 H 0 3
B & I
Ngay nay, ky thuat digital dUOc ap dung rong rai trong nhieu ITnh virc. Cac
mach digital dude dira vao sirdung trong hang loat cac san pham dien tif, nhi/ cac
thiet bi vien thong, may ti'nh, ti_r dong hoa, cac do choi co mach dien tCr, cac he
thong nghe nhin, do gia dung, dung cu do luting, dung cu y te va quan sir, cac tur
dien dien tCr_
Sach Ky thuat digital - ly thuyet va Crng dung gidi thieu nhCrng kien thud co
ban ve ky thuat digital va mot so irng dung trong doi song. Be tiep thu cac kien
thud de cap trong cuon sach nay, ban doc can co nhCrng kien thud pho thong ve
toan va ve mach dien tir. Ky thuat digital dude nghien ciru trutic hoac nghien cuti
song song v 6 i mon hoc dien tir co ban vi cac kien thud ve linh kien ti'ch cifc rdi rac
khong phai la dieu kien doi hoi trutic het.
Co the noi, cuon sach nay la ngirdi ban dong hanh cua cac ban ham thich
dien ti!r digital, cua cac cong nhan nganh dien tu” - vien thong va may ti'nh cGng nhif
cua cac cong nhan lanh nghe thuoc cac ITnh vu t co lien quan den cac mach dien
tu1digital. Cuon sach nay dirpc xem nhir la tai lieu tham khao hCru dung vi ti'nh thut
dung va de hieu cua no doi vdi cac sinh vien cao dang va dai hoc nganh dien tCr vien thong va may ti'nh.
Sach Ky thuat digital - ly thuyet va u"ng dung co 11 chirong. Chi/ong 1 khai
quat ve cac he thong so nhi phan, bat phan va thap luc phan, moi lien quan giCra
cac he thong nay vdi he thong so thap phan, chi/Ong nay cGng gidi thieu tong quan
cac ma diroc sCr dung trong ITnh vi/c vien thong va may tfnh. Chutfng 2 gidi thieu ve
dai so logic, phan tich va tong hop mach logic, cac djnh ly De Morgan, cac phifOng
phap toi gian mach bang bang Karnaugh, bang cac dinh ly va dinh luat cua dai so
logic. Chi/dng 3 gidi thieu cac mach xir ly so lieu, de cap den cac bo ghep kenh,
phan kenh, cac bo giai ma, ma hoa, bo tao va kiem tra bit chan le. Noi dung
Chi/ong 4 noi ve phep cong, phep trif so hoc, cac phep bu 1, bu 2 va cac bo niTa
cong va cong day du, de tirdo, ta hieu di/Oc can ke cac bo cong va bo trir. ChiTOng
5 gidi thieu cac ho IC TTL va CMOS, noi dung de cap trong phan nay giup ta co
cac kien th u t co ban de sCr dung co hieu qua va phoi ket hop di/oc cac ho IC TTL
va CMOS trong cac mach digital. Noi dung cac Chuting 6 , ChiTOng 7 va ChGOng 8
di/oc u'ng dung nhieu trong cac mach dien tu1 digital thong thuting. ChifOng 6 gidi
thieu cac loai flip flop RS, RS dong bo tTnh, flip flop D, flip flop JK va flip flop JK
Master-Slave; ngoai ra, con gidi thieu trigo Schmitt, loai trigo co dac ti'nh quan
trong, dude su' dung de tao nen cac xung nhip; Chudng nay cung gidi thieu cac
loai mach dao dong, mach tao xung nhip. Noi dung ChUdng 7 thirc chat la cac u’ng
3
dung dac ti'nh cua cac flip flop diroc ti'ch hap trong cac IC de thirc hien cac phep di
chuyen so lieu. Trong chirong 8 , noi dung diroc de cap la cac loai bo dem va cac
Mod dem; tir chirong nay, ta thay diroc cac cau true va cac iru nhiroc diem cua cac
loai bo dem. Chirong 9, bo nho ban dan va chirong 10, chuyen doi A/D va chuyen
doi D/A, hai chirong nay gidi thieu ve nhCrng nguyen ly cau tao co ban va cac dac
ti'nh cua cac bo nho ban dan, cac bo chuyen doi A/D va chuyen doi D/A, giup ta co
the Crng dung cac bo kien nay trong cac mach dien tir digital. Chirong 11 dira ra
mot so mach Crng dung ky thuat digital, nhir trong dung cu dem tan, do do rong
xung va trong dong ho digital... Co the xem chirong 11 nhir la mot so bai tap Ion,
Crng dung ky thuat digital, tir do, ta co the van dung ky thuat digital vao cac Crng
dung khac trong doi song hang ngay.
Voi dung y cuon sach Ky thuat digital - ly thuyet va Crng dung diroc viet de
pho cap rong rai kien thCrc ve digital, voi cach trinh bay de hieu, co nhieu vi du,
nhieu bai tap va loi giai. Tac gia rat mong cuon sach diroc dong dao cac cong
nhan lanh nghe cung nhir cac sinh vien cao d in g va dai hoc nganh dien tir - vien
thong va may ti'nh, cac ban yeu thi'ch ky thuat dien tir digital rut ra diroc nhCrng dieu
bo ich tu” cuon sach nay.
Trong qua trinh bien soan va in an, cuon sach khong the tranh khoi con
nhCrng thieu sot. Chung toi rat mong ban doc thong cam va gop y xay diing, de
trong Ian tai ban, cuon sach diroc hoan thien hon.
Chung toi xin gCri toi Ban Bien tap Nha Xuat ban Lao dong - Xa hoi loi cam on
chan thanh ve sir giup do qui bau cua Qui Ban, de cuon sach s 6 m dGOc ra m§t
ban doc.
DO KIM BANG
4
CHUONG 1
HE THONG SO VA M A
■
Hoc xong chuang nay, hoc vien co kha nang:
□ Hieu dwoc cac he dem thap phan, nhi phan,
bat phan va thap luc phan.
□ Chuyen doi d'uoc cac so tit he thap phan
sang cac he nhi phan, bat phan va thap luc phan
va ngwoc lai.
□ Tinh d'L/oc cac gia tri cua cac so phan
nguyen va phan phan tit cac he nhi phan, bat
phan va thap luc phan sang cac so tuong ditong
cua he thap phan va ngitdc lai.
□ Hieu diroc cac cau true mot so ma thong
thudng dung trong ky thuat digital.
TONG QUAN
Khi noi den so dem, moi ngirdi deu nghT ngay den he thap phan v 6 i 10 con
so: 0, 1,2, 3, 4, 5, 6 , 7, 8 , 9. May vi tinh hien dai khong xir ly so thap phan. Thay
vao do la he thong so nhi phan sir dung 2 con so: 1 va 0. Nhi/ng khi sir dung so
nhi phan, muon the hien mot so thap phan co tri so tirong doi Ion bang so nhi phan
thi so nhi phan do kha dai. Do do, ngirdi ta thirdng sir dung cac so bat phan va
thap luc phan de rut ngan chuoi so nhi phan.
Chirong nay trinh bay cac he nhi phan, bat phan va thap luc phan v 6 i muc
di'ch khong chi dem diroc cac so theo cac he dem tren day ma con nghien ciru
each chuyen doi tir he dem thap phan sang cac he dem nhi phan, bat phan va
thap luc phan va ngiroc lai. Chu’Ong nay cung de cap den cac ma nhi phan thirdng
diroc su' dung trong cac he thong digital.
5
1.1. SO NHj PHAN
Cac may vi ti'nh va cac he thong digital deu dira tren co so hoat dong nhi
phan (2 trang thai). Vi du, khoa chuyen mach trong Hinh 1.1a co the diroc dong lai
hoac mo ra. Do do, khoa chuyen mach la mot vi du ve thiet bi nhi phan don gian
nhat.
Tranzito trong cac mach dien tir dung trong cac he thong va cac may tinh
digital diroc thiet ke de hoat dong tirong hop v 6 i he thong nhi phan, do la hien
tirong ngirng dan hoac dan bao hoa cua tranzito. Ket qua la 6 ngo ra cua mach
tranzito co mot trong hai trang thai mire dien ap cao hoac mire dien ap thap. Khi
quan sat tin hieu digital tren may hien song thay dien ap hoac 6 m ut thap hoac 6
mire cao. Cac tin hieu digital nay thay doi mire dien ap khi may vi ti'nh hoat dong,
cac dien ap nay xuat hien nhir la cac xung (Hinh1.1b)
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a)
b)
Hinh 1.1. Cac vi du ve sir dung so nhi phan
Tom lai, cac khoa chuyen mach, cac tranzito va cac linh kien digital khac deu
dira tren co so he nhi phan. Oieu do noi len rang so nhi phan rat thuan tien khi
dung vao viec phan tich va tong hop cac mach digital. Ngoai ra, can biet cach dem
so nhi phan va chuyen doi so nhi phan ra thap phan va ngiroc lai.
1.2. CHUYEN DOI NHI. PHAN - THAP PHAN
Co the bieu dien so nguyen bat ky thanh cac so don vi, chuc, tram, nghin...
Vi du, so thap phan 2945 co the viet thanh:
2945 = 2000 + 900 + 40 + 5
( 1 . 1)
Bieu dien diroi dang luy thira cua co so 10, bieu thirc (1.1) co the viet lai la:
2945 = 2.103 + 9. 102 + 4. 10 1 + 5 10°
(1.2)
f
"
t
^
Vi tri cac con so
Moi vi tri con so trong day so 2945 co mot trong so va he so.
6
Cac luy thi/a co so 10 :103, 102, 101, 10° la cac trong so.
Cac so 2, 9, 4 va 5 la cac he so.
Ti'ch trong so va he so cho gia tri cua moi vi tri con so.
Tong tat ca cac ti'ch cho gia tri cua so thap phan do.
6
vi du tren, 2 nhan vdi trong so 1000, 9 nhan v6 i trong so 100, 4 nhan vdi
trong so 1 , tong so la:
2000 + 900 + 40 + 5 = 2945
- Trong so nhj phan
Bang cach tirong tir, ta co the viet lai mot so nhi phan nao do voi cac trong
so.
Vi du: so nhi phan 111 diroc viet la:
111 = 100 + 10 + 1
(1.3)
Bieu thirc (1.3) viet dirdi dang thap phan:
7=4 +2 + 1
(1.4)
Khi viet so nhi phan nhir trong bieu thirc (1.3) ta se lam mot viec tirong tir
phan doan so thap phan thanh don vi, 2s va 4s nhir trong bieu thirc (1.4).
So co trong so nho nhat diroc goi la LSD, so 1 6 ben phai, co trong so nho
nhat; so co trong so I6 n nhat diroc goi la MSD, so 4 6 ben trai day so co trong so
Idn nhat.
Noi cach khac, moi vi tri so cua so nhi phan co mot trong so. Vi tri thCr nhat 6
ben trai, so 1, (trong so nhoi nhat. Vi tri thCr hai tir ben phai co trong so 2, so ben
trai lien ben co trong so 4.
Cac trong so nay co so mu cua luy thira 2 tang len, do do, co the viet phirong
trinh (1.4) nhir sau:
7 = 1. 22 + 1. 2 1 + 1. 2°
Moi khi gap so nhi phan ta co the xac dinh diroc mot so thap phan tirong
dirong nhir sau:
1. Khi co so 1 6 mot vi tri con so, hay cong trong so cua vi tri do.
2. Khi co so 0
6
mot vi tri con so, bo qua trong so cua vi tri do.
Vi du, so nhi phan 101 tirong dirong vdi so thap phan la:
4 + 0 + 1 =5
Mot vi du khac, so nhi phan 1011 tirong dirong voi so thap phan la:
8 + 0 + 2 + 1=11
Phi/dng phap doi so nhj phan ra thap phan theo thu tuc sau:
1. Viet so nhi phan.
2. Viet tri/c tiep dirdi so nhi phan cac so 1, 2,4,
3. Neu co so 0
0
mot vi tri con so, xoa bo trong
8 , 16...va viet tu1phai
so 0 vi tri do.
qua trai.
4. Cong cac trong so con lai ta diroc so thap phan tirong dirong.
Vi du: Hay chuyen doi so nhi phan 101 thanh so thap phan tirong dirong:
B l/ oc 1: 1 0
1
B l/ oc 2:4
1
2
Bade 3: 4 (2) 1
B l/Oc 4: 4 + 1 =5.
Vi du: Hay chuyen doi nhanh so nhi phan dirdi day thanh so thap phan ti/Ong
dirong:
1 0
1 0
16 (8 )
4
1
(2)
1 = 21
- Phan phan cua so nhj phan
Ta da nghien ciTu phan nguyen. Vay phan phan cua so nhi phan diroc chuyen
doi thanh so thap phan tirong dirong nhir the nao?
Vi du, so thap phan nao tirong dirong vdi so nhi phan 0, 101? Trong trirdng
hop nay cac trong so cua cac vi tri tir phia phai dau phay cua so nhi phan la: 1 / 2 ;
1/4, 1/8, 1/16 v.v...
Neu viet diroi dang luy thira cua 2, cac trong so la:
2"1 , 2 "2 , 2 '3,
, v.v...
hoac dirdi dang thap phan la:
0,5; 0,25; 0,125; 0,0625; v.v...
->
^
f
O vi du nay, phan phan cua so nhi phan 0,101 la:
0
,
1
0
1
0,5
(0)
0,125
= 0,625
Vi du khac, so thap phan tirong dirong cua 0,1101 la:
0,
1
1
0
1
0,5
0,25
0
0,0625
=
0,8125
- So nhj phan hon hop
Doi vdi cac so hon ho'p (cac so co ca phan nguyen Ian phan phan) ta thirc
hien cac quy t§c chuyen doi da thao luan 6 tren cho cac phan nguyen va phan
phan. Cac trong so cua cac so hon hop la:
v V....23
22
21
2°,
2~1
2 "2
2“3
/
dau phay nhi phan
9
,
- Bieu do may vi tinh
Khi nghien cifu cac so nhi phan, ta hieu biet sau sac them ve cau tao ben
trong cua mot may vi tinh. Hinh 1.2 la cac phan co ban cua mot may vi ti'nh diroc
gidi thieu nhir sau:
Ngo vao: la noi dira chirong trinh va so lieu vao may, 6 may vi tinh ngo vao
bao gom ban phim de chuyen doi ky tir (chCr va so) thanh chuoi cac so lieu nhi
phan.
Bo nhd: la noi chirong trinh va so lieu diroc liru trir trudc khi tinh toan. Cung
vay, khi ti'nh toan, bo nhd liru tru” cac tra loi trung gian, tirong ti/ nhir cach ta v ln
lam khi ti'nh toan. Bo nhd cua may vi tinh gom co ROM (bo nhd chi doc) va RAM
(bo nhd viet va doc).
Dieu khien: phan nay cua may vi ti'nh trong qua trinh ti'nh toan khong nhd con
ngirdi can thiep vao. Phan dieu khien noi cho cac phan cua may vi ti'nh cach xir ly
so lieu nhir the nao.
^
Phep tinh so hoc va logic: phan nay la cong, trCr, nhan va chia. Phan nay
cGng thirc hien cac phep tinh logic nhir OR, AND, NOR, NAND v.v...
Ngo ra: la phan de chuyen Idi giai cuoi cung ra ben ngoai. Phan ngo ra cua
may vi ti'nh la man hinh cho phep ngirdi sir dung thay diroc cac so lieu da diroc xir
iy-
BO DIEU KHIEN
NGO VAO
BO NH0
KHOI SO HOC VA LOGIC
Tt
rr
Hinh 1.2: Cac phan co ban cua mot may vi ti'nh
9
NGO RA
v
Trong bang dirdi day thong ke cac luy thira cua 2 va so thap phan tirong
dirong cua chung, cung cac so K. Ky hieu K thay cho 1024. Do do, 1K bln g 1024.
2K bang 2048. 4K b ln g 4096 v.v... Nhieu may vi tinh ca nhan (PC) co cac bo nho
64K, dieu do co nghla la chung co the liru trir 65.536 byte trong phan bo nhd chi
ra 6 Hinh 1.2
Bang 1.1. Cac luy thira cua 2
CAC LUY THUA
CUA 2
SO THAP PHAN
CAC LUY THUTA
TUUNG OUtfNG
SO THAP PHAN
KY HIEU
TUtfNG BlTCfNG
CUA 2
2°
1.
28
256
21
2
29
512
22
4
2'o
1024
1K
23
8
2i ’
2048
2K
24
16
2«
4096
4K
25
32
2 1S
8192
8K
2s
64
2 14
16384
16K
27
128
215
65536
32K
1.3. CHUYEN DOI THAP PHAN - NHj PHAN
Cach chuyen doi so thap phan thanh so nhi phan tirong dirong la cach tien
hanh ngiroc vdi cach chuyen doi da di/oc mo ta 0 tren.
+ Vi du, muon chuyen doi so thap phan 9 thanh so nhi phan tirong dirong,
dieu can thirc hien la bieu thi diroc 9 la tong cua cac luy thira cua 2, roi viet 1 va 0
0 cac vi tri cua cac con so:
So thap phan
^
So nhi phan
►
9 =
8
+ 0 + 0 + 1
1 0
0
1
+ Mot vi du khac: Chuyen doi so thap phan 25 thanh so nhi phan tirong
dirong:
So thap phan:
^
So nhi phan:
►
25
= 16 +
1
1
8
+ 0 + 1
0
1
- Phirong phap chia tuan tir cho 2
Phirong phap pho bien de chuyen doi cac so thap phan sang nhi phan la
cach chia tuan tir so thap phan cho 2. viet so du” sau moi phep chia. Cac so dir
du'o'c slip xep theo thir tu ngu'dc se cho ta so nhi phan tuong dirong. Cach tot nhat
de hieu phirong phap nay la thirc hien vi du dudi day:
Cach chuyen doi so thap phan 53 ra so nhi phan nhir the nao?
10
Thi/c hien chia
Phan dir
53:2 = 26
1
26:2 = 13
0
13:2 = 6
1
6:2 = 3
0
3:2 = 1
1
1:2 =■ 0
1
So co trong so nho nhat (LSD)
o
♦o-o
'
So bat phan hon hop
011
Bat dau tif dau phay nhi phan, thu’c hien theo hai hirdng, tach cac bit thanh
nhom 3. Trong trirdng hop nay, them cac so 0 de cac nhom ben ngoai cung diroc
day 3 bit. Chuyen moi nhom thanh so bat phan tuting di/Ong.
1011,011012 = 13,328
Ket qua la:
Viec chuyen doi de dang tis bat phan thanh nhi phan va ngiroc lai co nhieu iru
viet vi lay tin ra hoac cho tin vao he thong digital it doi hoi ve cau true mach vi
chung de dang doc va in ra so bat phan hon la so nhi phan.
Mot iru viet khac nira la cac so thap phan Idn diroc chuyen doi de dang sang
nhi phan neu trirdc het chuyen sang bat phan, roi sau do chuyen sang nhi phan.
Vi du: chuyen doi so thap phan 363 thanh so nhi phan.
Tri/dc het doi sang bat phan
0
5
5
5
45
3
o
o*o
=3
-•
9
9
10
—>
A
154
15
“
>
F
16)2479
Ket qua la:
▼
o
XoD
13
•
7
100
@
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
X*X,X4
101
p
Q
R
S
T
U
V
w
X
Y
Z
110
a
b
c
d
e
f
h
i
.i
k
I
m
n
o
111
P
q
r
s
t
u
V
w
X
V
z
Sau do, chuyen doi cac tong nay thanh ma BCD
4
5
^
I
0100
0101
Nhir vay, 0100 001 la ma dir 3 thay the cho so thap phan 12. Mot vi du khac,
chuyen doi so 29 thanh ma du" 3:
2
9
+3
+3
5
12
1
0101
1100
Sau khi da cong 9 vdi 3, khong nho 1 vao cot ben ma chuyen doi nhir da tien
hanh d tren. Do do, 0101 1100 la ma dir 3 thay the cho so thap phan 29.
Mach ti'ch hop dung de chuyen doi ma dir 3 thanh thap phan thirdng dirpc
dung la 7443. IC TTL nay co 4 ngo vao cho ma dir 3 va 10 ngo ra cho so thap
phan (xem thong so cua IC 7443)
1.8. MA GRAY
Bang 1.4 gidi thieu ma GRAY, tirong Crng vdi so nhi phan. Moi so cua ma
GRAY khac vdi so trudc 1 bit. Vi du, d so thap phan tir 7 den 8 , so ma GRAY thay
19
doi tir 0100 den 1100, cac so nay chi khac 6 bit co trong so Idn nhat (MSB). Nhi/
trong mot vi du khac, so thap phan 13 va 14 dupe chuyen doi thanh ma GRAY la
1011 va 1001; cac so nay chi khac mot vi tri so (vi tri thu1 hai ke tir ben phai). Nhir
vay, trong toan bo ma GRAY, moi so chi khac 1 bit v 6 i so trirdc.
Ngoai ma du” 3 va ma GRAY, con co nhieu loai dang ma nhi phan, nhir ma
BCD, ma nay con dirpc goi la ma 8 4 2 1.
Bang 1.4: Ma Gray
THAP PHAN
MA GRAY
NH|PHAN
THAP PHAN
MAGRAY
NHI PHAN
0
0000
0000
8
1100
1000
1
0001
0001
9
1101
1001
2
0011
0010
10
1111
1010
3
0010
0011
11
1110
1011
4
0110
0100
12
1010
1100
5
0111
0101
13
1011
1101
6
0101
0110
14
1001
1110
7
0100
0111
15
1000
1111
20
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