This has animation..so better to download and then play in slide show view.

1. Counting devices
ME3114D -Computer Integrated Manufacturing
-Naik Aniruddha Murlidhar(B170164PE)
1
National Institute of Technology
Calicut
30-05-2020

2. Index:
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1. What is a counter?
2. Inside the counter
1. Building bock
2. JK Flip-flop
3. SR-latch as memory
3. Types of counters
1. Asynchronous Counter and Synchronous counter
4. Two bit asynchronous counter and applications

3. What are counters?
• “A counter is a device which stores
(and sometimes displays) the
number of times a
particular event or process has
occurred” – Wikipedia
Mechanical counter
Image source:
https://woodgears.ca/counter/
• Two types:
• Mechanical counters
• Electronic Digital counters
• Sequential Electronic circuit
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4. Building block of Counters:
• Combinational circuit and Flip-Flops as memory:
 Combinational circuit: A circuit where current o/p is dependent on
current I/p.
 Are actually sequential circuits
(Present output depends on present input and past output)
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5. JK flip-flop:
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JK flip flop
Image source : google

6. Memory:
NOR- SR latch and truth table
Image source : google
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NOR gate truth table
Image source : google

7. Types of counters:
• Synchronous counters:
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• Asynchronous( Ripple) counters:
• The first flip-flop is clocked by the external clock pulse and
the each successive flip-flops are clocked by output of the
previous flip-flop
• All memory elements are simultaneously triggered by the
same clock

8. Asynchronous counter:
R
S
CLK
Q
Q
Negative edge triggering flip-flops
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9. Synchronous Counter:
Negative edge triggering flip-flops
CLK
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( 1 1 ) ~ 3
(Q1 Q0 ) ~ decimal form
( 0 1) ~ 1
( 1 0 ) ~ 2
( 0 0 ) ~ 0

11. Two-bit asynchronous counter:
Image source: google
(animation is made in
power point)
• Negative edge
triggering
• The external clock is
connected to clock of
1st flip flop
• The output from first
flip flop is connected
to clock of next flip-
flop
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12. Two-bit asynchronous counter:
• Usually, clear input are connected together, so that a single pulses
can clear all the flip-slops before counting starts
• The 2-bit ripple counter circuit above has four different states, each
one corresponding to a count value.
• Thus, a counter with n flip-flops can have 2N states
• The number of states in a counter is known as its mod(modulo)
number.
• E.g. 2 bit counter is a mod-4 counter.
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13. What is a mod counter?
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• If the counter is ‘n’ mod counter, then it will count from ‘0’ to ‘n-1’
in cyclic order.
• And a n- bit counter means it is ‘2N ‘ that means it will count from ‘0’
to ‘2N – 1 ‘

14. Applications of Counters:
• To count number of events occurred
• Increment/ decrement count
• Generating timing sequences
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15. Thank you!
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