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<!--replace-end-7--><!--replace-end-4--><!--replace-end-1--></head><body><div class="ui fluid container universe"><!--replace-start-2--><!--replace-start-3--><!--replace-start-6--><div class="ui text container" id="zettel-container" style="position: relative"><div class="zettel-view"><article class="ui raised attached segment zettel-content"><div class="pandoc"><h1 id="title-h1">Flip-Flops</h1><p>A flip-flop is a type of <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: Latches"><a href="Latches.html">latch</a></span></span> that is connected to a <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: Clock signals"><a href="Clock_signals.html">clock signal</a></span></span> and which executes in time with the clock’s pulse. (Sometimes “latch” and “flip-flop” are used interchangeably but technically a latch is flip-flop without a clock connection.)</p><h2 id="jk-flip-flop">JK Flip-Flop</h2><p>The JK Flip-Flop (the letters are meaningless) is basically an SR latch in functionality. It has a “set” input (<em>J</em>) and a “reset” input (<em>K</em>) and <em>Q</em> and inverted-<em>Q</em> outputs.</p><p>Where it differs from the SR is that it the SR will change state just if the voltage is high (this, afterall, is all that a bit is) whereas for the JK to set it <strong>must receive a clock pulse</strong> and it will only set on the pulse. Hence in addition to <em>J</em> and <em>K</em> inputs it has a <em>CLK</em> input for “clock”.</p><p>In addition the JK Flip-Flop has a <strong>toggle</strong> function. When this is executed, whatever <em>Q</em> currently is will be flipped to its opposite value: <span class="math inline">\(1 \rightarrow 0\)</span>, <span class="math inline">\(0 \rightarrow 1\)</span>. The toggle executes when both <em>J</em> and <em>K</em> are set to high.</p><p>The possible state changes for the JK Flip-Flop are detailed below:</p><table class="ui table"><thead><tr><th>J</th><th>K</th><th>Clock</th><th>Q state</th><th>Operation</th></tr></thead><tbody><tr><td>0</td><td>0</td><td>Pulse</td><td>Maintain previous value</td><td>Hold</td></tr><tr><td>0</td><td>1</td><td>Pulse</td><td>0</td><td>Reset</td></tr><tr><td>1</td><td>0</td><td>Pulse</td><td>1</td><td>Set</td></tr><tr><td>1</td><td>1</td><td>Pulse</td><td>Inverse of previous value</td><td>Toggle</td></tr></tbody></table><p>A JK Flip-Flop can execute on either the positive or negative pulse. Below are the diagrams for a rising and falling pulse respectively:</p><p><img src="/static/jk-flip-flops.png" /></p><h2 id="t-flip-flops">T Flip-Flops</h2><p>Another type of Flip-Flop can be created by connecting the <em>J</em> and <em>K</em> inputs of a JK Flip-Flop to each other. This reduces the possible states to two: toggle current state or maintain current state. Its overall logic is therefore reduced to just two lines of the previous state table: the state that obtains when <em>J</em> and <em>K</em> are <span class="math inline">\(0 0\)</span> or <span class="math inline">\(1 1\)</span>.</p><p>Thus the state table for the T Flip-Flop is:</p><table class="ui table"><thead><tr><th>T</th><th>Clock</th><th>Q state</th><th>Operation</th></tr></thead><tbody><tr><td>0</td><td>Pulse</td><td>Maintain previous value</td><td>Hold</td></tr><tr><td>0</td><td>Pulse</td><td>Inverse of previous value</td><td>Toggle</td></tr></tbody></table><p><img src="/static/t-flip-flops.png" /></p></div></article><nav class="ui attached segment deemphasized backlinksPane" id="neuron-backlinks-pane"><h3 class="ui header">Backlinks</h3><ul class="backlinks"><li><span class="zettel-link-container cf"><span class="zettel-link"><a href="Three_bit_counter.html">3-bit Counter</a></span></span><ul class="context-list" style="zoom: 85%;"><li class="item"><div class="pandoc"><p>To demonstrate the use of <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: Flip-Flops"><a href="Flip_flops.html">Flip-Flops</a></span></span> we will create the circuit for a 3-bit counter. This simply counts up fro
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