[PD] triggered oscilloscope/bang on zero crossing?

Mike Moser-Booth mmoserbooth at gmail.com
Wed Dec 9 01:05:34 CET 2009

cyclone's [edge~] is useful for converting zero crossing to bangs:

[expr~ $v1<0]

The only downside is that it quantizes to the end of the block, but then 
again, so does [tabwrite~]. I actually attempted doing one with edge and 
posted it on the forum, if you're interested.



Derek Holzer wrote:
> I'm trying to put together a simple oscilloscope abstraction that 
> imitates the "trigger" function of a real one, so that the waveform 
> can be seen from its starting point.  In other words, a [tabwrite~] 
> would graph on the upward swing of a zero crossing. To do this, I'd 
> like to know if there is an audio object which gives a bang at a zero 
> crossing, or perhaps even only at a crossing from the negative to the 
> positive domain of the signal. I've thought of something with [expr~ 
> $v1 < 0], but what comes out is still in the audio domain and isn't 
> the bang which [tabwrite~] needs.
> Other suggestions welcome.
> best!
> Derek

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