Pad Response Timing?

[pfc]

I'm mucking about with a homepad design that has reasonably complex electronics between the pads an the controller. The electronics are going to introduce some delay between pressing down on the pad and the signal making it to the controller.

Currently, I'd guess that I have something of the order of 100 microseconds delay.

Does anybody know what timing requirements there are for Stepmania or the Playstation games for a step to be counted as marvellous? Is it related to the BPM?

If a fast song is 200BPM, (3.3 beats per second) and the fastest step is a semi-quaver (sixteenth note) then the pad needs to at least register 14 steps per second. If, for a marvellous, there's a 5% tolerance that's 280 samples per second, or a response time of around 3.5 miliseconds.

But those numbers are complete guesses. Does anybody have any actual data?

[pfc]

I seem to have found what I was looking for. Or data that's useful enough to give me an idea.

The Stepmania 3.9 rc3 included timing windows are (from data/StepMania.ini):
JudgeWindowAdd=0.000000
JudgeWindowScale=1.330000
JudgeWindowSecondsAttack=0.135000
JudgeWindowSecondsBoo=0.180000
JudgeWindowSecondsGood=0.135000
JudgeWindowSecondsGreat=0.090000
JudgeWindowSecondsMarvelous=0.022500
JudgeWindowSecondsMine=0.090000
JudgeWindowSecondsOK=0.250000
JudgeWindowSecondsPerfect=0.045000

zombiejesus9001 in <a href="http://www.cobaltflux.com/forum/viewtopic.php?t=1621">this thread</a> says the arcade machines are set at something like:
Marvelous window = 1/60 of a second
Perfect window = 2/60 of a second
Great window = 4/60 of a second
Good window = 5/60 of a second
Boo window = 8/60 of a second

So, to answer my own question, the window is absolute, not relative to the tempo of the song. For a marvellous, you have to hit the pad within about 20 ms of the beat.

More importantly, you can adjust the overall offset (JudgeWindowAdd), so even if my design does increase a delay as large as the order of 1 millisecond, it can be corrected. Please forgive my n00bishness.

[deM']