Triggered phasor playing just one period?

#1

I'm looking for a phasor that would play on trigger just one period (one ramp then stay at 0 or stay at "maximum").
I haven't found such an object, so I'm looking for pointers on how to detect the "wrapping around" of the phasor.
I'd like to detect when the addition of a phase-increment makes the phasor reach the "top" or when "the next phase-increment addition will wrap around and go back to zero-ish".
Thanks for any pointer/suggestion of object to study!

Make phazorFm play only one cycle
#2

A linear-slope AD envelope with 0 attack and whatever you want for decay sounds like what you need.

a|x

#3

Thanks for the idea. It could work in some cases, but I need that in S-Rate, with a strict progression and a vertical edge. If I use a K-rate envelope followed by interpolation, the vertical edge is smoothed over 16 samples. That's why I'm looking at a phasor-like implementation.

#4

Ah, good point. What you need then, is an S-Rate AD envelope. Not sure if that exists, but it shouldn't be hard to convert the K-Rate object to work at S-Rate (with 16x the CPU overhead, of course). I might give that a go myself, if I have a free moment this evening.

a|x

#5

Indeed, I'll try that, too. Thanks.

#6

Not that easy, since K-Rate envelopes use int32_t type and when it goes "<0".
A S-rate phasor code is super efficient, just a repeated addition on a frac32.buffer.positive type. For this reason, we can't detect "<0", nor "==0" (==0 depends on the exact phase increment).
Still wondering how to "stop" or "suspend" such a phasor at the right time. Will keep working on it...

#7

I think rbrt/old/1shot does what you're looking for. The only thing is that frequency is calculated as a range inside a given table, because has a very specific use. Maybe you can modify it to suit your needs...

#8

Check if the current value is lower than the current decrement value (assuming the value is being decremented from the 1>>27 to 0) and decrement if not.

a|x

#9

@valmir Thanks for the pointer, I'll look at that.
@toneburst Yes, that sounds like a great idea, will try!

#10

I should say, if current value is less than decrement value, set to 0, else decrement.

a|x

#11

Here is what I came up with. Thanks all for the help.
one-period-phasor-trig.axp (2.4 KB)