*Chng 4: HE TUAN TI. Gii thieu:Ngo vao (INPUT)Ngo ra (OUTPUT) He tuan t la he ma ngo ra khong ch phu thuoc vao cac ngo vao ma con phu thuoc vao 1 so ngo ra c hoi tiep tr thanh ngo vao thong qua phan t nh. Phan t nh thng s dung la Flip_Flop. He tuan t c chia thanh 2 loai: - He tuan t ong bo (Synchronous)- He tuan t bat ong bo (Asynchronous)

*II. Mach Chot (Latch) va Flip-Flop (FF):Flip_Flop: la mach tuan t ma no thng lay mau cac ngo vao va lam thay oi cac ngo ra tai nhng thi iem xac nh bi xung clock. Latch (chot): la mach tuan t ma no lien tuc xem xet cac ngo vao va lam thay oi cac ngo ra bat c thi iem nao khong phu thuoc vao xung clock.

*1. Cac mach chot:a. Chot SR: co 2 loai * Cong NOR: 0 00 11 01 10 11 0 0 0Bang hoat ong: Cam s dung Q+ la trang thai ke tiep cua QKy hieu:

** Cong NAND: Bang hoat ong: Ky hieu: 0 00 11 01 11 00 1 1 1Cam s dung

*b. Chot SR co ngo vao cho phep: 0 X X1 0 01 0 11 1 01 1 10 11 0 1 1Ky hieu chot SR co ngo vao cho phep tch cc cao: Bang hoat ong:

** Khao sat gian o xung: Q(Cho Q ban au la 0)Ky hieu chot SR co ngo vao cho phep tch cc thap: 1 X X0 0 00 0 10 1 00 1 10 11 0 1 1

c. Chot D: Ky hieu chot D: Bang hoat ong: 0 X1 01 10 11 0*

C DQ+ Q+

*2. Flip_Flop (FF): Trang thai ke tiep cua ngo ra FF se thay oi theo ngo vao va trang thai trc o cua ngo ra tai thi iem thay oi cua xung clock (canh len hoac canh xuong) * Bang ac tnh va phng trnh ac tnh: Bieu dien moi quan he cua ngo ra ke tiep Q+ phu thuoc vao cac ngo vao va trang thai ngo ra hien tai Q. * Bang kch thch: Bieu dien gia tr cua cac ngo vao can phai co khi ta can ngo ra chuyen t trang thai hien tai Q sang trang thai ke tiep Q+.Xung clock canh lenXung clock canh xuong

*a. Flip_Flop D (D-FF): Bang hoat ong: 0 11 0Khong thay oi 0 11 0Khong thay oi

CK D Q+ Q+

CK D Q+ Q+

** Khao sat gian o xung: * Bang ac tnh va phng trnh ac tnh:0 00 11 01 1 0011 * Bang kch thch:0 00 11 01 1 0101

D Q Q+

Q Q+ D

Q b. Flip_Flop T (T-FF): Bang hoat ong: 0 1 * Bang ac tnh va phng trnh ac tnh:0 00 11 01 1 0110* Bang kch thch:0 00 11 01 1 0110*

T Q+

T Q Q+

Q Q+ T

*c. Flip_Flop SR (SR-FF): * Bang hoat ong:0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 10* Bang ac tnh va phng trnh ac tnh:10 00 11 01 1 Q01X0011XX* Bang kch thch:0 00 11 01 1 0 X1 00 1X 0

S R Q Q+

S R Q+

Q Q+ S R

*d. Flip_Flop JK (JK-FF): * Bang hoat ong:0 00 11 01 1 Q01*0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 10* Bang ac tnh va phng trnh ac tnh:1001110* Bang kch thch:0 00 11 01 1 0 X1 XX 1X 0

J K Q+

J K Q Q+

Q Q+ J K

*e. Cac ngo vao bat ong bo: - Cac ngo vao nay se lam thay oi gia tr ngo ra tc thi, bat chap xung clock. - Co 2 ngo vao vao bat ong bo: Preset (Pr) va Clear (Cl).+ Khi ngo vao Preset tch cc th ngo ra Q c set len 1. + Khi ngo vao Clear tch cc th ngo ra Q c xoa ve 0. + Khi ngo vao Preset va Clear khong tch cc th FF mi hoat ong.

*III. Bo em (COUNTER):1. Gii thieu: - Bo em la he tuan t co 1 ngo vao xung clock va nhieu ngo ra. Ngo ra cua bo em chnh la ngo ra cua cac Flip-Flop cau thanh bo em. - Noi dung cua bo em tai 1 thi iem goi la trang thai cua bo em. Khi co xung clock vao bo em se chuyen trang thai t 1 trang thai hien tai chuyen sang 1 trang thai ke tiep. C tiep tuc nh vay se tao ra 1 vong em khep kn. - Gian o trang thai cua bo em: Bieu dien cac trang thai co trong vong em va hng chuyen trang thai cua bo em. - Modulo cua bo em: La so cac trang thai khac nhau trong vong em: m 2n

* * Bo em c chia thanh 2 loai:- Bo em noi tiep (bo em bat ong bo): la bo em ma ngo ra cua FF trc se la ngo vao xung clock cho FF sau. - Bo em song song (bo em ong bo): la bo em ma ngo vao xung clock cua cac FF c noi chung vi nhau. 2. Bo em noi tiep (Asynchronous Counter): : - Bo em noi tiep thc hien cac vong em len hoac xuong: + em len (Count Up): noi dung bo em tang them 1 khi co xung clock. + em xuong (Count Down): noi dung bo em giam i 1 khi co xung clock. - Bo em c tao t cac FF em 2, ghep noi tiep vi nhau.

*a. Bo em ay u (m = 2n): CKKhao sat gian o xung: ay la bo em len (Count Up)* Ghep Cki+1 = Qi

*CKKhao sat gian o xung: la bo em xuong (Count Down)

*CKCK+ Bo em xuong (Count Down):+ Bo em len (Count Up):

*b. Bo em khong ay u (m 2n): - Bo em khong ay u thc hien da vao bo em ay u. Ta can xac nh trang thai ke tiep khong mong muon cua vong em khong ay u. - Dung trang thai nay e tao ra tn hieu tac ong tch cc vao cac ngo vao bat ong bo Preset hoac Clear e a bo em tr ve trang thai ban au (thng gi la trang thai reset). Vd: S dung T-FF co xung clock canh xuong va ngo vao Preset, Clear tch cc cao; thiet ke bo em len co m = 5 va bt au t gia tr 0. 0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 1000001XXTa gi Z la tn hiu reset b m. Z1XXZ = Q2 Q0

Q2 Q1 Q0

*CK000Khao sat gian o xung: *

Vd: S dung JK-FF co xung clock canh xuong va ngo vao Pr, Cl tch cc thap; thiet ke bo em xuong co m = 5 va bt au t gia tr 2. 0 1 00 0 10 0 01 1 11 1 01 0 1Tn hiu reset:(tch cc thap)CK111

Q2 Q1 Q0

*3. Bo em song song (Synchronous Counter): : - La bo em ma cac FF eu s dung chung nguon xung clock; khi co xung clock vao th tat ca cac ngo ra FF eu thay oi. - Khi thiet ke bo em, ch quan tam en trang thai hien tai va trang thai ke tiep cua FF, ma khong quan tam en dang xung clock (canh len hoac canh xuong). - Co the thiet ke bo em co vong em bat ky. Bang ham kch thch:

** Cac bc thiet ke:- T phat bieu bai toan xac nh so FF s dung va day em.- Lap bang chuyen trang thai ch ro moi quan he gia trang thai hien tai va trang thai ke tiep (da vao day em).- Tm cac gia tr ngo vao FF can phai co t gia tr hien tai Qi va ke tiep Q+i cua tng FF (da vao bang kch thch cua FF).- Tm bieu thc rut gon cua moi ngo vao FF phu thuoc vao cac bien trang thai hien tai.- Thc hien s o logic.

Cac ngo vao FF

*a. Bo em ay u (m = 2n): Vd: S dung T-FF kch theo canh len, thiet ke bo em co day em sau: Q2Q1Q0 : 010, 101, 110, 001, 000, 111, 100, 011, 010, 0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 11 1 10 0 01 0 10 1 00 1 11 1 00 0 11 0 01010101010101111111111111111111111T0 = 1

*T0 = 1CK1

0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 1*b. Bo em khong ay u (m < 2n): Cac trang thai co trong vong em se thiet ke nh bo em ay u; con cac trang thai d khong co trong vong em se giai quyet theo 2 cach sau: * Cach 1: Cac trang thai d co trang thai ke tiep la tuy nh. Khi thiet ke can khi ong gia tr ban au cho bo em; gia tr nay phai la 1 trong nhng trang thai co trong vong em. Vd: Thiet ke bo em dung D-FF canh len, co ngo vao Pr va Cl tch cc cao, co gian o trang thai sau: 1 0 0X X X1 1 00 1 00 1 1X X X0 0 0X X XD2 D1 D0

T/t hien taiQ2 Q1 Q0T/t ke tiepQ+2 Q+1 Q+0

*CKRS

** Cach 2: Cho cac trang thai d khong co vong em co trang thai ke tiep la 1 trong nhng trang thai co trong vong em. 0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 11 0 01 1 01 1 00 1 00 1 11 0 00 0 01 0 0111010100100101101011101

T/t hien taiQ2 Q1 Q0T/t ke tiepQ+2 Q+1 Q+0Cac ngo vaoT2 T1 T0

** Phan tch bo em song song: - T s o logic cua bo em xac nh ham kch thch (bieu thc cua cac ngo vao cua tng FF phu thuoc vao cac ngo ra Qi) - Lap bang trang thai: t trang thai hien tai Qi va gia tr ngo vao ta xac nh c trang thai ke tiep cua FF Q+i. - T bang chuyen trang thai xac nh c gian o trang thai hoac khao sat gian o xung cua bo em.

*JA = QB QCKA = 10 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 1000100011111111101010000010111111111000011111111000100000110000010100000

T/t hien taiQA QB QCCac ngo vaoJA KA JB KB JC KCT/t ke tiepQ+A Q+B Q+C

*IV. Bo em thanh ghi dch (Shift Register Counter):1. Bo em vong (Ring Counter): 1 1 0 02 0 1 03 0 0 1

*2. Bo em vong xoan (Twisted-ring Counter): bo em JohnsonCK1 0 0 02 1 0 03 1 1 04 1 1 15 0 1 16 0 0 1

ClockQ2 Q1 Q0

*V. Thanh ghi dch (Shift Register): La thanh ghi ma d lieu cua no c dch 1 bit moi xung clock1. Thanh ghi dch nhap noi tiep - xuat noi tiep (SISO): SERINSEROUT2. Thanh ghi dch nhap noi tiep xuat song song (SIPO): SERIN

*3. Thanh ghi dch nhap song song - xuat noi tiep (PISO): SERIN

*4. Thanh ghi dch nhap song song - xuat song song (PIPO):

IC 74193

SIPO (74ALS164)

PISO (74HC165)

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