Flip-Flops.html (2806B)
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3 <html><head><link rel="stylesheet" href="sitewide.css" /><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><meta name="exporter-version" content="Evernote Mac 6.13.1 (455785)"/><meta name="altitude" content="-0.4269982278347015"/><meta name="author" content="Alex Balgavy"/><meta name="created" content="2017-11-09 1:14:25 PM +0000"/><meta name="latitude" content="52.33344899833077"/><meta name="longitude" content="4.868301745244982"/><meta name="source" content="desktop.mac"/><meta name="updated" content="2017-11-09 6:09:21 PM +0000"/><title>Flip-Flops</title></head><body><div><span style="font-weight: bold;">SR Latch</span><br/></div><div>Circuit of two NOR gates that can ‘remember’ which input was most recently 1 (in this case, R).</div><div>The state R = S = 0 is undefined, the state R = S = 1 is unused.</div><div><br/></div><div><img src="Flip-Flops.resources/screenshot_4.png" height="166" width="440"/><br/></div><div><br/></div><div><span style="font-weight: bold;">Gated SR Latch</span></div><div>When the time at which to set or reset is controlled by a clock instead of the inputs</div><div>When the clock is at 1, signals R’ and S’ change based on R and S.</div><div>When the clock is at 0, no change in the state can happen.</div><div><br/></div><div>Implementation with NAND gates? Just replace every gate with a NAND. It works. Trust me, I’m a computer scientist.</div><div><br/></div><div><img src="Flip-Flops.resources/screenshot_3.png" height="186" width="613"/><br/></div><div><br/></div><div><span style="font-weight: bold;">Gated D latch</span></div><div>Instead of using two separate inputs, you can derive the inputs from one input, D (data):</div><div><br/></div><div><img src="Flip-Flops.resources/screenshot_1.png" height="201" width="608"/><br/></div><div><br/></div><div><span style="font-weight: bold;">T flip-flop</span></div><div>changes state every clock cycle if its input T is 1 — “toggles state”</div><div><br/></div><div><img src="Flip-Flops.resources/screenshot_2.png" height="277" width="554"/><br/></div><div><br/></div><div><span style="font-weight: bold;">Master-slave flip-flop</span></div><div>What if you don’t want a change in the input to be immediately propagated to the output?</div><div>Connect two gated D latches to create a master-slave flip-flop.</div><div>While clock is 1, master is affected by changes in D but slave stays in the same state.</div><div>When clock changes from 1 to 0, output is propagated to the slave.</div><div><img src="Flip-Flops.resources/screenshot.png" height="297" width="583"/><br/></div><div><br/></div></body></html>