COUNTER Synchronous Counter 1 Objective To design a

COUNTER Synchronous Counter 1

Objective : To design a synchronous counter using J-K flip-flops. 2

Application of Counter? ? 3

Application of Counter? ? 4

Application of Counter? ? 5

Application of Counter? ? 6

Application of Counter? ? 7

Introduction • A counter – a group of flip-flops connected together to perform counting operations ( flip-flops are used to construct counters) • Two categories: 1) Asynchronous counter 2) Synchronous counter • Classification of counters - UP counter - DOWN counter - UP/DOWN counter 8

Introduction • A Synchronous Counter, is one whose output bits change state simultaneously, with no ripple. The only way we can design such a counter circuit from JK Flip-Flops is to connect all the clock inputs together, so that each and every flip-flop receives the exact same clock pulse at the exact same time: 9

How to design Synchronous Counter? ? • For synchronous counters, all the flip-flops are using the same CLOCK signal. Thus, the output would change synchronously. • Procedure to design synchronous counter are as follows: STEP 1: Obtain the State Diagram. STEP 2: Obtain the Excitation Table using state transition table for any particular Flip-Flop. Determine number of Flip. Flop used. STEP 3: Obtain and simplify the function of each Flip-Flop input using K-MAP STEP 4: Draw the circuit. 10

Example Design a synchronous counter (UP counter) with the binary count sequence shown in the state diagram of figure below. Use J-K flip flops 11

How to design Synchronous Counter? ? STEP 1: Obtain the State Diagram. • If present state = 00, so , next state = 01 • If present state = 01, so , next state = 10 • If present state = 10, so , next state = 11 • If present state = 11, so , next state = 00 12

How to design Synchronous Counter? ? STEP 2: Obtain the Excitation Table. State transition table Excitation table 13

How to design Synchronous Counter? ? STEP 3: Obtain and simplify the function of each Flip -Flop input using K-MAP For J 1 = Q 0 For K 1 = Q 0 14

How to design Synchronous Counter? ? STEP 3: Obtain and simplify the function of each Flip -Flop input using K-MAP For J 0 = 1 For K 0 = 1 15

How to design Synchronous Counter? ? STEP 4: Draw the Circuit Counter • • • 2 bit counter = 2 JK Flip-Flop From K-Map, J 0=K 0= 1 From K-Map, J 1=K 1= Q 0 Connect both flip-flop to the CLOCK signal Connect Q 1 and Q 0 to the BCD to 7 Segment CLOCK Q 1 Q 0 16

How to Design Synchronous Counter using software? ? DEMO…… 17

DOWN Counter? ? 18

How to design Synchronous Counter? ? STEP 1: Obtain the State Diagram. • If present state = 00, so , next state = 11 • If present state = 11, so , next state = 10 • If present state = 10, so , next state = 01 • If present state = 01, so , next state = 00 19

UP/DOWN Counter • Up counter and down counter is combined together to obtain an UP/DOWN counter. A control switch (S) input is also provided to select either up or down mode. • A combinational circuit is required to be designed and used between each pair of flip-flop in order to achieve the up/down operation. 20

UP/DOWN Counter Design up down counter based on sequence number below. when sw = 0, counter will count down sequence. when sw = 1, counter will count up sequence. 21

END…THANK YOU 22