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    Counters, Ripple Counters, Ring Counters

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    Amoga Lekshmi
    1. The document defines counters and classifies them as binary, ripple, and ring counters. It describes how a 4-bit binary ripple counter works using JK flip-flops and provides a timing diagram. 2. A ring counter is described as a circular shift register that shifts a single high bit between flip-flops to produce a sequence of timing signals. A 4-bit ring counter sequence is given. 3. Additional counter types discussed include Johnson counters, which are switch-tail ring counters combined with decoding gates to produce more output signals.

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    © All Rights Reserved
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    Counters, Ripple Counters, Ring Counters

    Uploaded by

    Amoga Lekshmi
    234 views16 pages
    1. The document defines counters and classifies them as binary, ripple, and ring counters. It describes how a 4-bit binary ripple counter works using JK flip-flops and provides a timing diagram. 2. A ring counter is described as a circular shift register that shifts a single high bit between flip-flops to produce a sequence of timing signals. A 4-bit ring counter sequence is given. 3. Additional counter types discussed include Johnson counters, which are switch-tail ring counters combined with decoding gates to produce more output signals.

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    4. Counters, Ripple Counters, Ring Counters

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    1. The document defines counters and classifies them as binary, ripple, and ring counters. It describes how a 4-bit binary ripple counter works using JK flip-flops and provides a timing diagram. 2. A ring counter is described as a circular shift register that shifts a single high bit between flip-flops to produce a sequence of timing signals. A 4-bit ring counter sequence is given. 3. Additional counter types discussed include Johnson counters, which are switch-tail ring counters combined with decoding gates to produce more output signals.

    Copyright:

    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    234 views16 pages

    Counters, Ripple Counters, Ring Counters

    Uploaded by

    Amoga Lekshmi
    1. The document defines counters and classifies them as binary, ripple, and ring counters. It describes how a 4-bit binary ripple counter works using JK flip-flops and provides a timing diagram. 2. A ring counter is described as a circular shift register that shifts a single high bit between flip-flops to produce a sequence of timing signals. A 4-bit ring counter sequence is given. 3. Additional counter types discussed include Johnson counters, which are switch-tail ring counters combined with decoding gates to produce more output signals.

    Copyright:

    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    of 16

    Synchronous Sequential Circuits

    A. Jawahar
    SSN College of Engineering
    Session Objectives

    • To define Counter and Classify the types of counter


    • To learn the operation of 4-Bit binary ripple counter,
    operation, timing diagram
    • BCD Ripple counter, operation, timing diagram
    • Three decade counter
    • To learn the operation of ring counter
    3

    Session Outcomes

    At the end of the session, students will be able to


    •Define and classify counters
    •Explain the working of a ripple counter with timing
    diagram
    •Derive the ring counter from the given counter

    27/01/23
    Counter: A register that goes through a prescribed sequence of
    states
    • Binary counter
     Counter that follows a binary sequence
     N bit binary counter counts in binary from n to 2n -1
    • Ripple counters triggered by initial Count signal
    • Applications:
     Watches
     Clocks
     Alarms
     Web browser refresh
    Counters- Introduction
    Counters are basically classified into two types based on
    how the clock is applied.
    (1) Asynchronous/Ripple Counters
    (2) Synchronous Counters
    Asynchronous/Ripple Counters:
    • The flip-flop output transition serves as a source for
    triggering other flip-flops.
    • The CP inputs of all flip-flops (except the first) are triggered
    not by the incoming pulses, but rather by the transition that
    occurs in other flip-flops.
    Synchronous Counters:
    • Input pulses are applied to all the CP inputs of all flip-flops.
    • Change of state of a particular flip-flop is dependent on the
    present state of other flip-flops.
    Binary Ripple Counter:
    o
    consists of a series connection of complementing
    flip-flops (T or JK type), with output of each flip-
    flop connected to CP input of next higher order
    flip-flop.
    o
    reset signal sets all outputs to 0.
    o
    small circle in C input indicates that the flip-flop
    complements during negative-going transition or
    when the output to which it is connected goes
    from 1 to 0.
    o lower order bit A → complemented with each
    0
    count pulse.
    o when A moves from 1 to 0 → complements A
    0 1
    o when A moves from 1 to 0 → complements A
    1 2
    o when A moves from 1 to 0 → complements A
    2 3
    and so on.
    o
    Flip-flops change one at a time in rapid
    succession, and the signal propagates through
    the counter in a ripple fashion.
    Logic-1
    A0
    J Q
    Count pulses
    K
     Binary counter with reverse count is
    called binary down-counter.
    A1
    J Q  Here the value is decremented with
    every input count pulse.
    K  Figure using JK & T flip-flops
    works as binary down-counter
    A2 (1) if outputs are taken from
    J Q
    complement terminals Q’.
    K (2) if all the flip-flops are
    triggered on the positive edge of the
    A3 pulse.
    J Q

    Fig. Binary Ripple Counter using JK flip-flop


    Timing
    1
    diagram:
    2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

    A0

    A1

    A2

    A3

    0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 0000
    (A3A2A1A0)
    • Ring counter:
    – a circular shift register with only one flip-flop being
    set at any particular time, all others are cleared
    (initial value = 1 0 0 … 0 )
    – The single bit is shifted from one flip-flop to the next
    to produce the sequence of timing signals.

    • A 4-bit ring counter A3 A2 A1 A0


    1 0 0 0
    0 1 0 0
    0 0 1 0
    0 0 0 1
    1 0 0 0
    • Application of counters
    – Counters may be used to generate timing signals to control
    the sequence of operations in a digital system.
    • Approaches for generation of 2n timing signals
    1. a shift register with 2n flip-flops
    2. an n-bit binary counter together with an n-to-2n-line decoder
    Johnson counter:
    • Ring counter vs. Switch-tail ring counter
    – Ring counter
    • a k-bit ring counter circulates a single bit among the
    flip-flops to provide k distinguishable states.
    – Switch-tail ring counter
    • is a circular shift register with the complement output
    of the last flip-flop connected to the input of the first
    flip-flop
    • a k-bit switch-tail ring counter will go through a
    sequence of 2k distinguishable states. (initial value =
    0 0 … 0)
    An example: Switch-tail ring counter
    • Johnson counter
    – a k-bit switch-tail ring counter + 2k decoding gates
    – provide outputs for 2k timing signals
    • E.g.: 4-bit Johnson counter

    – The decoding follows a regular pattern:


    • 2 inputs per decoding gate
    Summary

    • Counter definition
    • Types of counter
    • 4-Bit binary ripple counter, operation, timing diagram
    • BCD Ripple counter, operation, timing diagram
    • Three decade counter
    • Ring counter
    Practice Questions

    1. Differentiate between 4-bit ripple counter and ring counter.


    2. How modulo counter is different from ring counter?
    3. How many states 4-bit ring counter has? What modifications
    have to be done to count from 0000 to 1111?

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