Timing diagram


Joined Nov 30, 2010
I don't think so. Nobody taught me. I just looked at a timing diagram and understood it.

You start with a piece of paper and a sharp pencil. Graph paper works for me. Declare a horizontal line for each "point of interest", and label it well. Leave enough room between horizontal lines to represent positive and negative voltage (if that's what you have to work with). Declare a starting condition and mark that condition for each point of interest. Decide that time has passed so the next mark will be farther right, decide what changes first, and mark it. Then mark all the other points of interest as what would result at that time. Lather, rinse, repeat.

That's the best I can do. Maybe somebody else can do better.


Joined Sep 20, 2005
Well, think about what an RS latch does, find if it works on falling or rising edge of CLK or is level-triggered or asynchronous, and... suprisingly decide what the output is.


Joined Mar 14, 2008
Typically you draw the timing of the various inputs being used (clock, D, J, K, set, reset) on a readable scale. From that you use the behavior of the FF, latch, etc. to draw what the Q and /Q outputs are doing.

Thread Starter


Joined Oct 7, 2011
I'm not sure that I can do it correct... :( Can someone do for me example I have posted?
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Joined Jul 16, 2011
Here's an example I've just drawn.

The X (horizontal) axis shows time, which could be anything on an unmarked axis like this. Just remember that the further to the right you are on the x axis, the further in time you are.

The Y axis (vertical) shows voltage, or current. The higher the line is, the greater the current or voltage.

In this example, start at the origin (where both axis are 0). At this exact point we can see that when the time is 0 seconds, there is no voltage as the Y axis shows.

Moving across the X axis, we are now going forward in time, look at the labels, 1, 2, 3 seconds from the start.

Between 0 and 2 seconds we can see that the voltage has been increasing steadily to 5 volts. Moving further forward in time, the level line shows what?

It shows that the voltage has stayed the same over this second because the line has not moved up or down the voltage scale, but has moved along the time scale by one second.

What has happened between 3 and 5 seconds? The straight line at 3 seconds tells us that the voltage has suddenly dropped to 0 volts. As we just learnt a level line means that the voltage level hasn't changed. By looking at the x axis, we can see how long the circuit has stayed at 0 volts.

The answer should be clear as two seconds, the difference between 5 and 3 seconds.

Suddenly, we see the line move up again at 5 seconds suggesting a sudden increase in voltage back to 5 volts. It stays at 5 volts for the rest of the time which the graph shows, up to 9 seconds.

I hope this has been helpful.