sequential circuit

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Sequential Circuit

Introduction to Counter Asynchronous Counter - Ripple Asynchronous Down Counter Synchronous Counter – Parallel Synchronous Counter Up/Down Designing Synchronous Counter Counter with Parallel Load

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Sequential Circuit

Contents Register Introduction

Simple register Register with parallel load

Shift Register Shift Register Serial In/Serial Out Shift Register Serial In/Parallel Out Shift Register Parallel In/Serial Out Shift Register Parallel In/ Parallel Out

Two way shift register Random Access Memory

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Sequential Circuit: Counter

Introduction Counter is a circuit which cycle through state sequence Two types of counter

Synchronous counter (e.g. parallel) Asynchronous counter (e.g. ripple)

Ripple counter let some flip-flop output to be used as clock signal source for other flip-flop

Synchronous counter use the same clock signal for all flip-flop

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Asynchronous Counter (Ripple) Asynchronous Counter : flip-flop doesn’t

change condition simultaneously because it doesn’t use single clock signal

Also known as ripple counter because clock signal input as ripple through counter

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Asynchronous Counter (Ripple) Example: 2-bit ripple counter Output from one flip-flop is connected to clock input for the

next flip-flop MSB

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Asynchronous Counter (Ripple) Example: 3-bit ripple counter

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Asynchronous Counter (Ripple) Example: 4-bit ripple counter (negative edge triggered)

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Asynchronous Down Counter The previous example is up asynchronous counter Down asynchronous counter count from large to zero and

repeat Example: 3-bit binary down counter

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Asynchronous Down Counter Example: 3-bit binary down counter (MOD 8)

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Synchronous Counter (Parallel) Synchronous counter: flip-flop with the same synchronous

clock signal We can build synchronous counter using process to design

sequential circuit Example: 2-bit synchronous binary counter (using T flip-

flop or JK)

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Synchronous Counter (Parallel) Example: 2-bit synchronous binary counter (using T flip-

flop or JK) cont….

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Synchronous Counter (Parallel) Example: BCD Synchronous Counter

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Synchronous Counter (Parallel) Example: BCD Synchronous Counter

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Up/Down Synchronous Counter Up/Down Synchronous Counter: two way counter which

able to count up or down Up/Down control input line which determine the counter

Up/Down = 1 (count up) Up/Down = 0 (count down)

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Up/Down Synchronous Counter Example: 3-bit Up/Down Synchronous Counter

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Up/Down Synchronous Counter Example: 3-bit Up/Down Synchronous Counter (cont)

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Designing Synchronous Counter See sequential logic lecture notes Example: 3-bit Gray Code Counter (using JK flip-flop)

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Designing Synchronous Counter 3-bit Gray Code Counter: flip-flop input

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Designing Synchronous Counter 3-bit Gray Code Counter: logic diagram

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Counter with Parallel Load Counter with Parallel Load able to

Count at different condition Count in different sequence For increment/decrement function

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Counter with Parallel Load Different method to get MOD-6 counter

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Counter with Parallel Load Counter with 4-bit parallel

load

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Sequential Logic

Contents Register Introduction

Simple register Register with parallel load

Shift Register Shift Register Serial In/Serial Out Shift Register Serial In/Parallel Out Shift Register Parallel In/Serial Out Shift Register Parallel In/ Parallel Out

Two way shift register Random Access Memory

sequential circuit

Documents

way counter

parallelasynchronous

rippleripple counter

counter mod

synchronous binary counter

ripple counter output

asynchronous counter

flipflopsynchronous