The document discusses counters in digital electronics, detailing types such as synchronous and asynchronous counters, as well as their design procedures and modulus. It outlines the counting process, including incrementing and decrementing, and provides steps for designing both ripple (asynchronous) and synchronous counters. Additionally, the document concludes with references for further reading on digital electronics.

1. Counters
Contents:
 Counters
 Its types
 Modulus of counter
 Design procedure
 Examples
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2. Introduction
• A counter is register capable of counting the
number of clock pulses arriving at its clock input.
• Count represents the number of clock pulses
arrived.
• On arrival of each clock pulse , the counter is
incremented by one.
• In case of down counter , on arrival of each clock
pulse, it is decremented by one.
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3. Types of counter
• Synchronous counter
when counter is clocked such that each flip-flop
in the counter is triggered at the same time, the
counter is called synchronous counter.
• Asynchronous /ripple counter
consists of series connection of complementing
flip flops, with the output of each flip-flop
connected to the clock input of the next higher
order flip-flop
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4. Modulus of counter
• The total number of counts or stable states a
counter can indicate is called ‘modulus’
• Mod 6 – states 0 to 5
• Mod 4 – states 0 to 3
• Decade counter
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5. Design of ripple (asynchronous)
counters
Steps involved in the design of asynchronous
counter:
Determine the number of flip-flops needed.
Choose the type of flip-flops to be used: T or
JK
Write the truth table for the counter.
Derive the reset logic by K-map simplification.
Draw the logic diagram.
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7. Design of synchronous counters
• Determine the number of flip-flops needed. If n
represents number of flip-flops 2n≥Number of states
in the counter
• Choose the type of flip-flops to be used.
• Using excitation table for selected flip-flop determine
the excitation table for the counter.
• Use K-map or any other simplification method to
derive the flip-flop input functions.
• Draw the logic diagram.
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12. Conclusion:
The synchronous and asynchronous counters design procedure
with examples has been briefly explained.
References:
• Mandal, “Digital Electronics Principles & Application,
McGraw Hill Edu, 2013.
• William Keitz, Digital Electronics-A Practical Approach with
VHDL, Pearson, 2013.
• Thomas L.Floyd, ‘Digital Fundamentals’, 11th edition,
Pearson Education, 2015.
• D.P.Kothari,J.S.Dhillon, ‘Digital circuits and Design’,Pearson
Education, 2016.
• A.P.Godse., Dr.D.A.Godse, ‘Digital Logic Circuits’ , Technical
Publications Third Edition 2016
• Other Web Sources
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