COUNTERS
Presented by:- Shamshad Alam
Roll No.:- 40
rd
ECE 3 year
:- CONTENTS:-
INTRODUCTION
WHAT IS COUNTER ?
TYPES OF COUNTER
ASYNCHRONOUS Vs SYNCHRONOUS COUNTER
TRUTH TABLE & STATE DIAGRAME
APPLICATION OF COUNTERS
PRACTICAL EXAMPLE OF COUNTER
BIBILIOGRAPHY
INTRIDUCTION
• Counters are the crucial hard ware components.
• Counter circuit are made using flip flop.
• Counters have modes. The ‘mod’ of the counter represents the number of states of the
cycles through it, before setting the counter to its initial state.
• E.g A binary mod 4 counter has 4 count states, from 000 to 011. So the mod 4 counter
counts from 0 to 4. This means, in general a mod N counter can contain n number of flip
flops, where 2n = N.
WHAT IS COUNTER ?
The digital circuit which is used to count the number of pulses are formaly
called the counter (Timers) .
Counting means incrementing or decrementing the values of an operator,
with respect to its previous state value. We cannot perform this action
(counting) with any other logic devices rather than counters.
DIGITAL COUNTER
TYPES OF COUNTER
• Asynchronous Counters
• Synchronous Counters
• Up And Down Counter
• Decade Counter
• Ring Counter
• Johnson Counter
ASYNCHRONOUS UP/DOWN COUNTER
• The asynchronous is the simplest in term of logical operation there for it is easiest to design.
• Here the clock pulse is applied to first flip flop and the successesive f/f are triggerd by the
output of the previous out put thus the counter has the cumulative settling time
Truth table for up/down counter
SYNCHRONOUS UP/DOWN COUNTER
• In synchronous counters, the clock inputs of all the flip-flops are connected together and
are triggered by the input pulses. Thus, all the flip-flops change state simultaneously (in
parallel).
• Synchronous circuit is easy to design.
00 01
11 10
Present State Next State
A B A B
0 0 0 1
0 1 1 0
1 0 1 1
1 1 0 0
DIFFERENCE
SYNCHRONOUs ASYNCHRONOUS
• The propagation delay is very low. • Propagation delay is higher than that of
• Its operational frequency is very high. synchronous counters.
• These are faster than that of ripple • The maximum frequency of operation is
counters. very low.
• Large number of logic gates are required • These are slow in operation.
to design • Less number of logic gates required.
• High cost. • Low cost.
• Synchronous circuits are easy to design. • Complex to design.
DECADE COUNTER
• decade counter can be constructed with JK flip flop. The J output and K outputs are
connected to logic 1. The clock input of every flip flop is connected to the output of next flip
flop, except the last one.
• When the Decade counter is at REST, the count is equal to 0000.
• The NAND gate output is connected to clear input, so it resets all the flip flop stages in
decade counter. This means the pulse after count 9 will again start the count from count 0.
Truth table
• The NAND gate output is connected to clear input, so it resets all the flip flop stages in
decade counter. This means the pulse after count 9 will again start the count from count 0.
Ring Counter
• The ring counter is a cascaded connection of flip flops, in which the output of last flip flop is
connected to input of first flip flop. In ring counter if the output of any stage is 1, then its re
• Initially, all the flip flops in ring counter are reset to 0 by applying CLEAR signal. Before
minder is 0. The Ring counters transfers the same output throughout the circuit.
• Ring counters are used to count the data in a continuous loop.
Johnson Counter
• The Johnson counter is a modification of ring counter. In this the inverted output of the last
stage flip flop is connected to the input of first flip flop. If we use n flip flops to design the
Johnson counter, it is known as 2n bit Johnson counter or Mod 2n Johnson counter.
PRACTICAL EXAMPLE OF COUNTERS
• We use counters in many applications. Where ever we come across the use of timers, there
we use counters of synchronous type.
• in our kitchen appliances, we use microwave ovens. In that we set some temperature to
heat the food item kept in it. Internally the counter calculates the increase or decrease in
temperature and time. If it reaches the pre-set temperature, then it prevents from further
heating and spoiling of that food item.
washing mashines microwave ovens
PROGRAMMABLE LOGIC CONTROLLER (PLC)
• programmable controller is a digital computer used for automation of typically industrial
electromechanical processes.
APPLICATION
• Frequency counters
• Digital clocks
• Analog to digital convertors.
• With some changes in their design, counters can be used as frequency divider circuits. The
frequency divider circuit is that which divides the input frequency exactly by ‘2’.
• In time measurement. That means calculating time in timers such as electronic devices like
ovens and washing machines.
• We can design digital triangular wave generator by using counters.
BIBLIOGRAPHY
I have collected the content from google and different websit which is
given below as:-
https://www.google.co.in
https://en.wikipedia.org
www.crystalgraphic.com
www.image.com
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Thank
you
