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For my master thesis, I need to measure the propagation delay of the modules of my implementation. I use Quartus II to do so. My goal is to measure the critical path of my modules. I have read a lot of topics that say that I need to use the TimeQuest Timing Analysis tools but it is too complex for me (I'm more a computer science engineer than en electrical one). I search and I have found that Quartus performs a computation of the propagation delay which is what I need. I have found on this website all the details :

http://quartushelp.altera.com/14.0/mergedProjects/report/rpt/rpt_file_multicorner_timing.htm

Unfortunately, it doesn't answer all my questions. Effectively, I can clearly see what is a transition from rising edge to falling edge (a transition from 1 to 0) and from falling edge to rising edge (a transition from 0 to 1). However, I cannot see what is a transition from rising edge to rising edge and from falling edge to falling edge. I suppose that it doesn't mean that the signal doesn't change (since there wouldn't be any propagation delay).

Can someone explain me what is this transition ?

Thank you !

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    \$\begingroup\$ "a transition from rising edge to falling edge" is not "a transition from 1 to 0" because a transition from 1 to 0 only involves one edge i.e. it is the fall time. \$\endgroup\$ – Andy aka Mar 23 '16 at 11:20
  • \$\begingroup\$ Ok, I see what you mean. Is that correct that a transition from a rising edge to a falling is a transition from 0 to 1 then from 1 to 0 ? \$\endgroup\$ – user1382272 Mar 23 '16 at 11:28
  • \$\begingroup\$ @user1382272 Easy: The transition from 0 to 1 is a rising edge. \$\endgroup\$ – Dzarda Mar 23 '16 at 11:35
  • \$\begingroup\$ If you don't have concern about rising and falling edge and you only have concern about timing analysis (propagation delay) only then Quartus II will generate one report in Time-quest which will specify critical to short all path timings, but keep in mind that it is specific to platform (board) you are supposed to give at New Project Wizard. \$\endgroup\$ – Prakash Darji Mar 23 '16 at 12:25
  • \$\begingroup\$ @PrakashDarji This is exactly what I need. I have specify a platform and I will perform all my measurement on it. Do you remember in which directory I can fin the critical path timings ? \$\endgroup\$ – user1382272 Mar 23 '16 at 14:22
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I think you have transition times and propagation delays mixed up.

Transsition time refers to the speed of edges, while propagation delay refers to the time it takes for a signal to go through some device.

For example, output transition time generally refers to the time it takes for an output edge to go from a high to a low or from a low to a high (two different spec's by the way), while input transition time refers to the maximum time allowable for an input to be driven from a low to a high or from a high to a low and still have the device meet its switching time specs.

Propagation delay is an entirely different thing and and is the time it take for a device's output to go high (or low) once its input has been driven.

For example, consider an ideal inverter with a maximum propagation delay of 10 nanoseconds with an input which has just transitioned through Vcc/2. In order to meet the 10 nanosecond propagation delay spec, its output must transition through Vcc/2 in less than or equal to 10 nanoseconds.

But, since a picture is worth a thousand words, from TI,

here's the crux of it

enter image description here

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  • \$\begingroup\$ Thank you for your additionnal information. I have learned what it is the propagation delay but not the transition time ! \$\endgroup\$ – user1382272 Mar 23 '16 at 14:23

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