Digital I/O pins and Option for Extra Digital & Analog I/O

While I wait for my V4 kit I have read about the digital and analogue I/O custom options but have not seen anything written about peoples’ applications or documentation. Literally all I could find was the font page blurb.

Includes 4 customizable digital I/O pins. Optional extra 16 digital I/O pins, 8 analog inputs/outputs.

Is there a guide to how to customise in the right Zynthian sort of way without breaking the platforms function ? How do you connect & access optional I/O? etc

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some discussion here.

I’m not aware of too much development but I’m pretty sure there is a prototype out there somewhere!
It relies on A/D & D/A modules and is definitely part of official rig.

IT probably got a little eclipsed with all the recent brew ha ha over coronavirus etc and the step sequencer also became an obsession for a while.

How it’s all integrated into the system is frequently down to experimenters, it wasn’t so long ago that we were adding extra in ports for switches and now we have that as part of the v4 kit, so now is probably a good time to describe how you would like it to function.
Certainly I’m after volume pedal functionality at the very least and probably much more besides.

Hope this helps.

I’m only new here and thought I might have overlooked something. I guess the obvious things are stomp/momentary pedals, sustain pedal, CV I/O, MIDI clock.

Would be great to document the interface to connect your own custom stuff and how to access the digital and I/O functions without bringing it all down in a screaming heap. Maybe some sort of case study or application note as a how to.

The stomp on momentary, sustain is already functioning altho’ it’s implemented as MIDI control and via the keyboard bindings.


This is where the open source aspect of the project takes over. We need use cases, it’s easy enough to define it broadly, but it’s the configuration that is where the real insights are required. Quite how a volume pedal hooks in is quite detailed. Do we provide it as a layer?, do we add a provide an overall downstream lv2 facility , and how do we control it, do we use MIDI 7 and implement it that way or do we need floating point precision in our control signals perhaps we actually want ring modulation :smiley: ?
we are are after all in the territory of analog mixing so we could have some rather complicated concepts like average to take into account… .

All to be worked out. and that’s just a volume pedal.

The most useful thing people can do is get the beast flying even if it’s just an old Pi3 with on board audio and a hdmi or vnc connection.
Because that when we get real insight.

i2C seems to be how most things get handled eventually, so that’s probably the area that would benefit most from careful documentation. Often the only element required for additional features are few extra contexts and bit of extra config code in the webconf and a branch in the code base. We flatter ourselves that we can get musicians looking at code and coders playing as musicians, which is why we LOVE to hear sound samples indicated by :face_with_monocle:

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I got it working from first hearing about the project to running on a RPi 3B+ within 48h. With it just using internal audio, a mouse + MIDI controller & audio/video over HDMI to my TV was enough to blow my socks off and commit to a V4 kit asap. Being able to use it stand alone I think is where it will excel. But the 3B+ might be good for prototyping.

Next project is to do the same with a Pi Zero W with USB audio.

Never got it running on a Pi Zero W but didn’t really persevere. I was looking to produce an audio-less zynth for remote control purposes for which a Pi Zero W would be great, but I tend to have four or five projects running at any one time and simply rotate round them. I’m still trying to puzzle out how to turn 13 switches on Rasp Pi GPIO pins into a reliable pedal board, for 30 minutes I think it’s I2C and for th next half hour it’s GPIO pins :smiley:

Occasionally I play music. . .