数字电路教学课件：Chapter4-6.ppt

文档介绍：Lecture Notes
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Examples of Simple Counters
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Relative Occurrences of Events
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., Fig ***@P285
Producing Timing Pulse based on counter
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74xx393
Negative Edge Sensitive
4-bit Binary Counter
Counting Up:
0000 0001 0010 …… 1101 1111
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Sampled by Clock Edge
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Numbering Clock Pulse
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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Counting Up
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
E1=Σ(2,3,8,9,10,11)
E2=Σ(5)
E3=Σ(9)
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Logic Diagram
Step 1
Logic expression reduction
Step 2
Draw the diagram(74xx393 plus basic gates)
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., Pulse Duration
assume the period of CP is 200ns
the period of E1 is 1600ns
the duty cycle ratio of E1 is %
duty cycle = duty cycle ratio = duty-to-cycle ratio = ratio of ridge width to period
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MSI counter
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