The document discusses different types of counters used in logic design including decades counters, binary counters, up-down counters, BCD counters, and ring counters. It provides examples of synchronous and asynchronous binary counters, BCD counters with parallel load, and specialized counters like Johnson counters. Key aspects covered are how the counters work by toggling flip-flops to count in binary or BCD. Diagrams illustrate the circuitry and signal flow for different counter configurations.

1. LOGIC DESIGN
Counters

4. Decades Counter
Q3 Q2 Q1 Q0
BCD
Counter
100’s Digit
Q3 Q2 Q1 Q0
BCD
Counter
10’s Digit
Q3 Q2 Q1 Q0
BCD
Counter
Count
(CLK)
1’s Digit
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5. Synchronous Binary Counter
Q3
Q2
Q1
Q0
Enable
Q
Q
J
Q
J
Q
J
Q
To
Next
Stage
J
K
Q
K
Q
K
Q
K
CLK
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6. Up-Down Binary Counter
Q3
Q
Q
Q2
T
Q1
Q
Q
T
Q0
Q
Q
T
Q
T
Q
CLK
Up
Down
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7. BCD Counter
0
0000
0
1
0001
0
1
0010
0
1
0011
0
1
0100
1
1
1001
1000
1
0
0111
1
0
0110
1
0101
1
0
0
0
Q3 Q2 Q1 Q0
E
7 / 28

8. BCD Counter
0
0000 / 0
0
1
0
0001 / 0
1
0010 / 0
0
1
0011 / 0
0
1
0100 / 0
1
1
1001 / 1
1000 / 0
1
0
0111 / 0
1
0
0110 / 0
1
0101 / 0
1
0
0
0
Q3 Q2 Q1 Q0
y
E
8 / 28

9. Binary Counter with Parallel Load
CLR
LD
Count
Q(t+1)
0
x
x
0
1
0
0
Q(t)
1
0
1
Q(t)+1
1
1
x
I
I3
Q3
I2
Q2
I1
Q1
I0
Q0
LD
Count
CLR
Usually Asynchronous Clear
9 / 28

10. BCD Counter Example
LD
0
Q3
A3
0
I2
Q2
A2
0
I1
Q1
A1
0
Count
I3
I0
Q0
A0
Count
CLR
1
CLK
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11. Ring Counter
0001
T3 T2 T1 T0
0010
0100
1000
CLK
T0
2-to-4 Decoder
T1
T2
2-bit counter
T3
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12. Johnson Counter
0000
0001
0011
0111
1000
1100
1110
1111
Q3
Q1
Q2
Q
Q
D
Q
Q
D
Q0
Q
Q
D
Q
D
Q
CLK
12 / 28

13. Binary Counters
• Binary Counters do exactly what it sounds like they should.
They count in binary.
• Binary numbers are comprised of only 0’s and 1’s.
Decimal QD
QC
QB
QA
0
1
2
3
4
5
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
0
0
0
0
0
0
20 March 2007
Electronic Instrumentation
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14. Binary Counters are made with Flip Flops
DCBA = 1100
DCBA = 1111
Each flip flop corresponds to one bit in the counter.
Hence, this is a four-bit counter.
20 March 2007
Electronic Instrumentation
14

15. Typical Output for Binary Counter
1100
=12
DCBA = 1100
DCBA = 1111
• Note how the Q outputs form 4 bit numbers
20 March 2007
Electronic Instrumentation
15