I want to build a patch which acts like the gate input of eurorack's "maths" module, with dedicated rising and falling times at the beginning of a gate signal resp. at the end.
I.e. a square wave will get kind of a trapezoidal signal form with specific rise and fall times.

For testing purposes I made the following simple patch where the phasor's frequency can be changed. The threshold~ sends a bang and a small 1ms square wave signal is synthesized with the vline~.
But there seems to be an upper limit of the frequency of around (at least on my computer) 350Hz. Can not hear a tone with a higher pitch, with lower frequencies there is a kind of FM sound.
My question is: where is the problem in generating bang frequency higher than 350Hz? What is an alternate patch to get a bang signal at the raising edge of a signal and another second bang signal at the falling edge (like in threshold)?

Bangs exist in the control signal domain, which are limited by block size (64 samples by default). The fastest you can output two bangs is blocksize times 2, i.e. 128 samples. 44100/128 = 344.53Hz. You could make a subpatch and use the [block] object to reduce the blocksize...

If the effect you are after is a pulse (controllable freq) with adjustable slopes (and pulsewidth), there are ways to do that just using phasor, clipping and some smart math. I can't remember the design off the top of my head but I have it lying around somewhere in my mess...

Found it

SlopedPulse.pd

@obiwanke Here's another way using [slop~]: pulseGeneratorWithSlop~.pd

Thanks to both of you - very helpful and fast. Seems like this is what I was searching for. @bocanegra, thanks also for the explanation.

Could you achieve this with t3 objects from iemlib ( [t3_line~], [t3_del~] ) ? Just wondering.

@LucienR

Could you achieve this with t3 objects from iemlib ( [t3_line~], [t3_del~] ) ? Just wondering.

You would run into the same problem the OP describes as the t3 objects are triggered by control messages (see my first reply).

Also note that the [t3_del] object is now called [t3_delay] (which hasn't been updated in the help files)