Multichannel expander on full size Bela

resynth

Hi, I've got 2 Bela systems both already boxed in Hammond cases. My Bela mini system has no space to fit the multichannel expander but my full size Bela is in a large enclosure with plenty space for the expander as well as extra jacks etc. Rather than start again with the Bela mini it's making sense for me to try and get the multichannel expander working with the big Bela.

I had a look for the multichannel expander schematics so I could work out where to plug in my jumper leads but had no luck. Will these be on github anytime?
Is this idea theoretically possible or am I likely to fall victim to unknown unknowns?!

thanks 🙂

giuliomoro

oh didn't notice we didn't have the schematics up, will upload them later today. It can be done in theory, however some of the signals involved are pretty high frequency (24MHz MCLK clock, 11.289MHz data lines and SCK), so jumper wires could lead to signal quality issues (I have had mixed results when prototyping). A passive adapter PCB could be a better solution.

resynth

giuliomoro jumper wires could lead to signal quality issues

hadn't thought of that, thanks!

eyeversuseye

Did the expander pinout diagrams get removed recently? I can't find the pinout for bela audio expander. The full sized version

giuliomoro

I'm not sure that ever had a proper pinout

I think these are the only pages that ever existed on it:
https://github.com/BelaPlatform/Bela/wiki/Using-the-Audio-Expander-Capelet
https://learn.bela.io/products/accessories/audio-expander/

The pinout is the same as the Bela cape, with - in addition - the additional audio I/Os that are labelled on it.