Understanding Digital Design
The Random Number Generator
© 2014 Project Lead The Way, Inc. Digital Electronics
Random Number Generator
Digital Design - Demo
2
This presentation will
• Review the Board Game Counter block diagram.
• Review the circuit design of the sequential logic
section of the Board Game Counter.
• Review the circuit design of the combinational logic
section of the Board Game Counter.
Random Number Generator
Block Diagram
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0 0 0 1 1 1
0 1 1 0 0 1
1 0 1 0 1 0
1 2 3 4 5 6
Analog Section Sequential Logic Section Combinational Logic Section
The Analog Section produces a dampened square wave that “rolls” the count and slowly stops.
On every pulse of the clock, the Sequential Logic Section
increments a binary count from 1 to 6, then repeats.
The Combinational Logic Section
encodes the binary count into the die’s seven dots. CLOCK L1 L2 L3 L4 L5 L6 L7 A B C
Random Number Generator
Block Diagram
4 Analog Section Combinational Logic SectionThe Analog Section produces a dampened square wave that “rolls” the count and slowly stops.
On every pulse of the clock, the Sequential Logic Section
increments a binary count from 1 to 6, then repeats.
The Combinational Logic Section
encodes the binary count into the die’s seven dots. L1 L2 L3 L4 L5 L6 L7 Sequential Logic Section CLOCK A B C
Sequential Logic Section
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Schematic Diagram
CLOCK
A B C
3-Bit Counter
Default Count Range (010 = 0002 to 710 = 1112)
Set / Reset Logic
Changes Count Range (110 = 0012 to 610 = 1102)
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CLOCK
Functional Test (1 of 6)
Count of “1” (A=0; B=0; C=1)
Logic ‘0’ Logic ‘1’
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CLOCK
Logic ‘0’ Logic ‘1’
Sequential Logic Section
Functional Test (2 of 6)
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CLOCK
Logic ‘0’ Logic ‘1’
Sequential Logic Section
Functional Test (3 of 6)
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CLOCK
Logic ‘0’ Logic ‘1’
Sequential Logic Section
Functional Test (4 of 6)
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CLOCK
Logic ‘0’ Logic ‘1’
Sequential Logic Section
Functional Test (5 of 6)
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CLOCK
Logic ‘0’ Logic ‘1’
Sequential Logic Section
Functional Test (6 of 6)
Random Number Generator
Block Diagram
12 Sequential Logic Section CLOCK Analog SectionThe Analog Section produces a dampened square wave that “rolls” the count and slowly stops.
On every pulse of the clock, the Sequential Logic Section
increments a binary count from 1 to 6, then repeats.
The Combinational Logic Section
encodes the binary count into the die’s seven dots. Combinational Logic Section L1 L2 L3 L4 L5 L6 L7 A B C
Combinational Logic Section
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A B C
Schematic Diagram
Combinational Logic Section
Note: Because L1 / L5, L2 / L6, & L3 / L7 are always on together, only one combinational logic circuit was required for each pair.
Combinational Logic Section
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Truth Table
A B C L1 L2 L3 L4 L5 L6 L7
0 0 0 - - -
-0 0 1 0 0 0 1 0 0 0
0 1 0 0 0 1 0 0 0 1
0 1 1 1 0 0 1 1 0 0
1 0 0 1 0 1 0 1 0 1
1 0 1 1 0 1 1 1 0 1
1 1 0 1 1 1 0 1 1 1
1 1 1 - - -
-“1”
“2” “3”
“4” “5”
Combinational Logic Section
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Truth Table
A B C L1 L2 L3 L4 L5 L6 L7
0 0 0 - - -
-0 0 1 0 0 0 1 0 0 0
0 1 0 0 0 1 0 0 0 1
0 1 1 1 0 0 1 1 0 0
1 0 0 1 0 1 0 1 0 1
1 0 1 1 0 1 1 1 0 1
1 1 0 1 1 1 0 1 1 1
1 1 1 - - -
-Again, note that L1 /
L5, L2 / L6, & L3 / L7
have the same
entries in the truth
table; therefore, they
are equal functions.
Combinational Logic Section
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A = 0 B = 0 C = 1
Logic ‘0’ Logic ‘1’
Functional Test (1 of 6)
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A = 0 B = 1 C = 0
Logic ‘0’ Logic ‘1’
Functional Test (2 of 6)
Count of “2” (A=0; B=1; C=0)
Combinational Logic Section
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A = 0 B = 1 C = 1
Logic ‘0’ Logic ‘1’
Functional Test (3 of 6)
Combinational Logic Section
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A = 1 B = 0 C = 0
Logic ‘0’ Logic ‘1’
Functional Test (4 of 6)
Combinational Logic Section
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A = 1 B = 0 C = 1
Logic ‘0’ Logic ‘1’
Functional Test (5 of 6)
Combinational Logic Section
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A = 1 B = 1 C = 0
Logic ‘0’ Logic ‘1’
Functional Test (6 of 6)
Combinational Logic Section
Using LEDs
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A = 1 B = 0 C = 0
Shown with a count of “4” (A=1; B=0; C=0)
LED – Light Emitting Diode
Random Number Generator
Digital Section
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Sequential Logic Section
Combinational Logic Section
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