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75 lines
2.4 KiB
Markdown
75 lines
2.4 KiB
Markdown
---
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title: "sequential-circuits"
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aliases:
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tags:
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- cosc204
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---
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[combinatorial-logic-circuits](notes/combinatorial-logic-circuit.md) always produce the same outputs given the same input. Sequential curcuits on the other hand, produce different outputs depending on past history and the inputs.
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There are two main types of sequential circuit
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- Sychronous
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- this is when changes of state occur in time with a clock cycle
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- changes of input occur between clock pulses
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- state changes occur at the clock pulses
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- Asynchronous
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- state changes occur as the inputs occur
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- event driven
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# Main circuits
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## SR latch
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The set reset latch is the most basic and simple sequential circuit. It is anychronous
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The ouput is remembered and changed basic on previous output.
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- When S (set) is pulsed Q is one and Q̄ is zero
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- When R (reset) is pulsed Q is set to zero and Q̄ is set to one
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## D Flip FLop
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The D flip flop is basically an SR connected to a clock. Making it synchronous.
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Instead of switching when you set or reset. The outputs change when the clock pulses. Depending on the value of the D(ata) input.
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[circuit simulation](https://tinyurl.com/2cafc57y)
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## T Flip Flop
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The T flip flop swtiches between the two outputs Q and Q̄ when
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- T(oggle) is held high
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- And the clock is cycled (from off to on to off)
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## JK Flip Flop
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The JK flip flop is a combination of the d flip flop and the t flip flop.
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| J | K | Result |
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|:--|:--|:----------|
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| 0 | 0 | No Change |
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| 0 | 1 | Set |
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| 1 | 0 | Reset |
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| 1 | 1 | Toggle |
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It can be used as a toggle *and* as a d flip flop.
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## Synchronous Counter
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## Video demonstration of some sequential circuits
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<iframe width="560" height="315" src="https://www.youtube.com/embed/I0-izyq6q5s?start=84" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
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