Understanding Analog Design The Random Number Generator © 2014 Project Lead The Way, Inc.Digital...

Understanding Analog DesignThe Random Number Generator

© 2014 Project Lead The Way, Inc.Digital Electronics

Random Number GeneratorAnalog Design - Demo

2

This presentation will• Review the Random Number Generator block

diagram.

• Review the circuit design of the analog section of the Random Number Generator.

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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

AnalogSection

SequentialLogic

Section

CombinationalLogic

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

L1L2L3L4L5L6L7

A

B

C

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AnalogSection

CLOCKCombinational

LogicSection

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.

L1L2L3L4L5L6L7

SequentialLogic

Section

A

B

C

Random Number Generator Block Diagram

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Schematic Diagram

CLOCK

Random Number Generator Analog Section

A Simplified Version

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• When the push button switch is pressed, the 100uf capacitor (C1) will quickly charge to 5 volts through the 1.2 k resistor (R8).

• As long as the push button switch remains pressed, top end of the 10 k resistor (R9) will be held at 5volts. This results in a simplified version that is equivalent to a standard 555 time oscillator.

Actual Version Simplified Version

Analysis of Simplified Version

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nF 470 C k 18 R k 10 RBA

mSec 982.14T

nF 470 k 182k 10 693.0T

C R2R 693.0TBA

Hz 66.74 ƒmSec .T

ƒ

98214

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Period:

Frequency:

RAA

RB

C

Simulation of Simplified Version

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VOUT

VC

Simplified Version – Timing Analysis

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mSec 15T

Hz 66.66 ƒmSec

ƒ

Tƒ

151

1

Period:

Frequency:

VOUT

VC

The Actual Version

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• When the push button switch is pressed and held, the actual analog section of the Board Game Counter performs like a standard 555 time oscillator. However, for the Board Game Counter to operate correctly, the oscillation must slow and eventually stop.

• This is where the 100uF capacitor (C1) and the 1.2 k resistor (R8) play a role.

Actual Version Simplified Version

Simulation of Actual Version

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VOUT

VC

VLimit

PushButton Pressed

PushButton Released

Actual Version – Timing Analysis

• When the push button is pressed, the 555 Timer produces a 66 Hz square wave.

• Once the push button is released, the frequency gradually decreases (period increases).

• Eventually the oscillation will stop.

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VOUT

VC

VLimit

PushButton Pressed

PushButton Released

A CB

Timing Analysis at Time A

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A

mSec 536.15T

Hz 64.36 ƒT

ƒ

1

Period:

Frequency:

Timing Analysis at Time B

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B

mSec 50.27T

Hz 36.36 ƒT

ƒ

1

Period:

Frequency:

Timing Analysis at Time C

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C

mSec 429.51T

Hz 19.44 ƒT

ƒ

1

Period:

Frequency:

16

SequentialLogic

Section

CombinationalLogic

Section

Analog Section

Discussed in a future lesson

Random Number Generator Analog Section