19 votes 19 votes The number of flip-flops required to construct a binary modulo $N$ counter is __________ Digital Logic gate1994 digital-logic sequential-circuit flip-flop digital-counter fill-in-the-blanks + – Kathleen asked Oct 4, 2014 recategorized Apr 25, 2021 by Lakshman Bhaiya Kathleen 6.3k views answer comment Share Follow See 1 comment See all 1 1 comment reply Nitesh Singh 2 commented Dec 29, 2018 reply Follow Share binary modulo n counter means Asynchronous mod n up/down counter. 0 votes 0 votes Please log in or register to add a comment.
Best answer 33 votes 33 votes Let say we have to design a mod-$8$ counter i.e $000$ to $111$. So we need $3$ bits to represent i.e $3$ FF. For mod $N: 2^x = N$ $\implies x = \left \lceil (\log_2N) \right \rceil $ Praveen Saini answered Feb 27, 2015 edited Apr 23, 2021 by Lakshman Bhaiya Praveen Saini comment Share Follow See all 10 Comments See all 10 10 Comments reply mcjoshi commented Sep 6, 2016 reply Follow Share I have a doubt: if it is possible to form mod 8 counter using 3 FF. Why do we use Ring Counter or Johnson counter? 7 votes 7 votes junk_mayavi commented Nov 14, 2017 reply Follow Share to make mod8 ring counter, we will need 8 FFs. 3 votes 3 votes Niraj Singh 2 commented Dec 13, 2017 reply Follow Share this is for asynchronous counter 0 votes 0 votes tusharp commented Dec 11, 2018 reply Follow Share Counter Flip flops Counting Ring N mod(N) Johnson N mod(2N) Asynchronous N mod(2^N) I think here type of counter should be explicitly mentioned to find number of flip flops. @Shaik Masthan 6 votes 6 votes Shaik Masthan commented Dec 11, 2018 reply Follow Share actually, the counting sequence is not in order for Ring or Johnson ===> we can't use them for requirement of the question ! the one and only choice is Go with asynchronous counter ===> ⌈log$_2$n ⌉ 3 votes 3 votes soumayan bandhu commented Jan 30, 2019 reply Follow Share @Shaik Masthan for ring counter and johnson's counter is the output of left flipflop is MSB? And also please mention which is the MSB for asynchronous UP and down counter. 0 votes 0 votes Shaik Masthan commented Jan 30, 2019 reply Follow Share in GATE exam, they will specify which is LSB and which is MSB 3 votes 3 votes Doraemon commented May 10, 2020 reply Follow Share @Shaik Masthan Sir. According to me we can also construct a synchronous binary mod N counter. and it will have ceil(logn ) counters. Counters can have any sequence of states. And here binary mod N counters means that it follows binary sequence like (0-1-2-3-4..... upto 2^n-1 )and then this cycle repeats. According to Morris Mano "A counter that follows binary sequence is called binary counters" Am I correct? 0 votes 0 votes Abir Mazumder commented Sep 22, 2020 reply Follow Share A simple mod N counter that counts from 0 to N-1 , so either you use a synchronous or asynchronous approach , you will be needing LogN FF . The only difference will be the amount of additional circuitry that will be needed in case of a synchronous counter. 1 votes 1 votes Abhrajyoti00 commented Jan 6, 2023 reply Follow Share To construct a binary modulo $N$ counter, we need to store the current count in the counter. The number of bits needed to store a number in binary is equal to $log_2(N)$, where $N$ is the maximum number that can be stored. 0 votes 0 votes Please log in or register to add a comment.