OWL Pedal, Push button compatibility

Hi, I just got an OWL Pedal, and I noticed that the factory Preset: ‘ACID Groovebox’ assumes that there is a way to send a clock to the Push button input - which isn’t there on the OWL Pedal. Pressing the Push button repeatedly isn’t a very good solution. Have you considered a different factory patch set for the OWL Pedal?

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It’s a good point. The ACID Groovebox was added to show a different way of using the device, but it’s true that it doesn’t make much sense without a trigger input.
Two thoughts come to mind: modify the patch so that it runs at its own tempo, but syncs to a tap.
Or modify it to (also) use the expression input as clock source. That way you could patch in a clock on the pedal if you wanted to, from something like a Volca. Would have to be tested to work with the hardware.

OK. I’ll see what I can come up with along these lines…

On the tap tempo thing, I’ve seen that just adding an input across the Push switch isn’t ideal. Is there an ‘approved’ method of adding a ‘Push’ input (copy the circuit from the Modular?)

You mean to add the hardware for a trigger input?
On the modular we use a transistor buffer to protect the inputs and translate the level.

Yep, that’s what I meant. I haven’t spent enough time looking at the circuits yet… so this is a useful kick-start. There’s a very obvious jack-socket-sized space inside the case…

OK, so if I copy the modular transistor buffer, the ‘TR-IN/IN_D’ circuit leading to PBZ (and then PB6) through Q901, will this then work in a pedal as a ‘Push button’ press when asserted (+5v)? (Or does the Digital board know if it is inside a Modular or a Pedal, and so reject any ‘Pedal’-sourced PB6 assertions?)

Yes the firmware is slightly different on the Modular and Pedal.

The transistor inverts the signal, so when the input goes high it pulls the pin PB7 low. The Modular firmware configures an internal pull-up on PB7 and triggers an interrupt when it changes.

The circuit connecting to PB6 is for the trigger output on the Modular and can be ignored.

What you could do is copy the input circuit (one jack, 3 resistors and one NPN transistor e.g. 2N3904) and either

  1. connect it to PB7 on the digital board of your OWL Pedal and compile a custom firmware version, or
  2. connect it to PE2, the switch input, and use the stock Pedal firmware

with 2) any incoming trigger or gate will appear to the pedal as a button press. Beware that this also means that if the gate is long enough, it will trigger the pedal to change patch just as when you hold down the button!

If you want to try out 1) then I can perhaps help by compiling a firmware image if you like.

I prefer to avoid custom firmware whenever possible, so option 2 is my preference, and is what I wanted to do right from the start. I will build it up and test it.

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OK. Here’s the first prototype of a ‘Footswitch-to-Push-button’ input for the OWL Pedal, built more or less as described in this thread. It seems to work fine with ‘Normally Closed’ ‘Roland’-style footswitches. Documentation to follow soon…

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OK. You can find the write-up for the footswitch-to-push-button ‘extra socket’ in my blog here:

As usual with this type of mod, you do this at your own risk. Take care!

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That’s an excellent mod and a brilliant write up. Nice work!

I have now added a tutorial on how I wrote the ‘Four Step Sequencer’ patch in Gen, for the Owl Pedal (with the foot-switch controlling the tap tempo) to my blog:

I would be interested in feedback from Gen users on this forum. Thanks!

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