I think the idea of an expansion header, breaking out some of the Ksoloti’s unused pins was discussed briefly on Mod Wiggler.
I wondered if there are any plans to add this to a future revision of Big Genes?
One obvious candidate for a BG expander that could be connected to such a header would be a multi-channel gate/trigger expander, but perhaps more CV I/O could also be provided this way.
I can share custom object code for a similar 8-output expander for the old Euxoloti Axoloti Eurorack module, if that would help (though obviously the BG hardware would need to be modified to support such expanders).
Unused pins (and shared-ly usable pins) are broken out:
Power: +/-12V, 5V, 3.3V, GND
PA15: digital IO, PWM output
PB3, PB4: digital IO, PWM output, SPI, SPILink
PB8, PB9: I2C
PC5: digital IO, analog in
PD5, PD6: digital IO, USART, SPI, SPILink
I’ve had ideas for
a gate/trigger expansion
a gate/CV expansion
a button matrix.
would be cool to have a expansion focusing on a playable UI, like with touch strips and RGB LED feedback… one is allowed to dream here.
Even cooler for me personally would be some sort of protoboard-like expander where users can align their own layout, like what the Synthux Simple Designer Kit is doing. Something you can solder yourself without spending a lot of thought about wiring and routing. But then this does not seem to appeal to many.
You’re right, object code is an important question as the hardware will only ever be as good and usable as the objects using them.
It even has “EXPANSION HEADER” written in MASSIVE letters… sorry… I feel very stupid, now. In my defence, I was at work, and my Big Genes at home, and I couldn’t see it in any of the renderings on the build docs page. Poor defence, I know…
Is there perhaps enough space to move the header into the clear area near R35, or even rotated 90deg. where the EXPANSION HEADER label is?
Are surface-mount 90deg. 1.27mm headers a thing? That might help if so with the header in its current location, as you could attach an expander without having to remove the Core board.
All good ideas!
Yes, that’s it! It was a later addition, but there’s a version of the front panel (the one I have) that aggregates the Euxoloti and GAT8.
I can’t seem to download the PDF you link to, for some reason, so I don’t know what it says. I do know there was a shift-register involved, and I think it only used a couple of pins (+ pwr, gnd) on the Axoloti.
The other alternative might be to use the expansion header to transmit/receive MIDI. That would make the expanders attached to them more complicated, of course, but would add flexibility. The Euxoloti control surface was connected to the Axoloti via MIDI.
Some good defense! I think about features all the time without the thing in front of me, too.
Technically yes, it just feels like asking for trouble, running those several high-frequency signals and analog power so close to the digital switching power regulator (U2 and friends).
Apparently not, and although through-hole ones are a thing, those again are a bit bigger and routing is again more messy and meh.
Ya know, I am all for big-a§§ 2.54mm through hole headers, it just didn’t work out here. Maybe I can find another position or solution, but I need to keep the current format and pinout, as changing it would be unfair to everyone who already bought a kit so far.
I can see how it’s challenging, given the density of hardware on the top of the mainboard. It’s great there are so many controls, but I understand design is about finding the best compromises, in a lot of cases.
Good point, too. But you’re still open to moving it, if that turns out to be possible, as long as the pinout remains the same?
It’s not a massive deal, of course, as it’s not like people will need to change expanders often, I guess. I’me always wary of mechanical stress when pulling boards apart when they’re connected with many header pins though, so if the expansion header could somehow be moved clear of the Core footprint, that would be cool.
Good point, sure I’d like to move it too at least so it’s clear of the Core, the pinout should stay but moving it or making it angled (or possibly increasing pitch, board-side) would definitely be nice. I’ll have a movey when i have the time, see how it goes.
This caught me out once with another DIY build, with a really dense cluster of headers connecting two boards. I was finding I had to reflow the header solder every time I pulled the boards apart during assembly.
So there is something like this option as well. Still would require a new PCB unfortunately, but at least the location of the header would not need to move.
That is true, but I think they can be made a bit more resilient. Take the Raspberry PI camera connector cable. I’ve folded those in the past w/out issue.
