New Axoloti prototype

#41

Very very nice! Just voicing my support and probable interest in a group buy.

#42

Good point! I am not familiar with exp pedals, looks like they are just a potentiometer? I also see different wirings and pinouts, is there a most common wiring?

#43

unfortunately not really. you are right that these are normally just potentiometers. and the most common is a stereo jack connection, but the wiring is not really standard, the more expensive pedals have a switch to accommodate for different polarity... so if you go for the standard TRS you should be fine: http://expressionpedals.com/how-expression-pedals-work

#44

Generally they behave just like a pot and can be wired as such. I have one axoloti with an axocontrol board where I used the two axis joystick points. Since I have the same pedal twice, I can't say much about variations, but all that I've seen are 'switchable' where polarity is concerned and tend to have a fine tuner pot.

#45

And here's a picture. one input is for a momentary switch and the three wire is the expression pedal.

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CW —— Sleeve
Wiper — Tip
CCW —– Ring

I believe. Edit. Nope. Just looked. The wiring above is Wiper to ring. So RTS, not TRS. Don't know why. Both could work with the ehx expressions I use. Those are just 10k pots but have a range adjustment, polarity switch and a 'rev' direction switch.

#46

Cool, EHX seems like a good starting point. With the polarity and direction switches most instruments should be covered. Now that I think about it I once was looking for an expression pedal compatible with an Ensoniq EPS keyboard and I remember that one was unusual... I'll go back and check the service manual

#47

Some devices require CV where the control voltages are generated by the pedal. That's a way to generate income :slight_smile:

I just too a look and some cheap devices (< 50) have polarity switches.https://www.thomann.de/intl/behringer_fcv100_v2.htm although generally it's the >100 ones that have more options.

#48

yippeee! So, I have two prototypes running now, after a bit of struggling with the correct order of flashing. So far, just great!

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#49

exciting! this thread confirms my strategy of dusting off my old music tech box :slight_smile: fyi, nektar expression pedals are great for $20 & work w my EHX and Boss pedals.

#50

Oh that reminds me, this Gill Stalks thing works. Though I feel I did not have to make it this small. Maybe move the jacks to the back, give it a 9V power input, and a stompbox foot switch ...

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#51

Cool. If you insist :slight_smile: I think it's always tricky to get a hat right the first time and 'generic' is really difficult. I've always wanted to build something modular where you can swap parts out, but that's non trivial. I think N buttons, N knobs and some lights does cover a lot of use cases. maybe we could open (or find an old thread) where the wish list for layouts was distilled?

#52

That's a really good tip. Very inexpensive. I've found some cheap expression pedals frustrating, but I also have some expensive ones (Yamaha) that are a real pita. So, for 22 Euro, the NX-P is really worth trying. Thanks!

#53

Meanwhile I have sound from the PDM microphone (looks like I forgot to mention the current version of the board has one) but get a LOT of hiss and very quiet. Unusable really. There would be more coding and filtering involved to make it sound good. I found Johannes did some coding around PDM and I used his objects as a foundation after messing around with some other approaches.

I am thinking to get rid of the PDM on board as no matter how, this would take up precious resources on the MCU even if the mic is not used in your patch. Alternatively I only now learned that the hardware codec on the Axoloti/Noloti can interface directly with a PDM mic and you could switch via an object between stereo line in and the mic (you can only have either line in L+R or the mono mic, not both simultaneously. However you could switch between both by loading a new patch).

[obsolete] Axoloti PDM microphone
#54

i think having the pdm instead of the input by choice would still be great. a mic on board is great for prototyping new ideas and can be of use for interactive installations as well

#55

Done! Rerouted the two mic lines to the codec. Now the GPIOs PB3 and PB4 are all clean and not double-assigned anymore. Should have read the ADAU1961 datasheet more thoroughly!

#56

That's excellent! I would love to buy this board when it is released. I can't wait.

#57

Good gods, never thought the forum would be up again. Quick, I'll try to send a crawler through the content to back up as much as possible.

#58

v0.3 prototype will be here soon and has seen many many small improvements under the hood. Hope it is still as straightforward as the earlier ones.

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#59

very excited - will chip in and support this when it comes up....

#60

Yeah I'm happy that the forum is back but these episodes are getting longer and longer.
Where can we check the update of your projects elsewhere than this forum in case it goes down?