Hi @zynthianers!
I’ve found this fantastic site, that is a blow of fresh air and inspires my creativity for future kit improvements:
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Yeah, really nice. I particulary appreciate the way where the excellent job is mixed with some dirty looks 
This could also be inspiring: RPI compute module is out !
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The new compute module looks good & the pricing is great. They have changed the main connector from the earlier compute module; it still looks like a difficult connector to solder to a daughter board. A Zynthian daughterboard with audio codec, encoders and I/O connectors would be fun to design… but hard to specify & assemble.
Would be neat if someone made a compute module hat. That would be an interesting expansion.
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Using the compute module would allow more compact design and plays well to the product rather than project but it has disadvantages. Compute modules tend to arrive more than a year after the standard board which can delay development of new features. It is less accessible for hobbiests, i.e. needs extra hardware (motherboard) to expose its interfaces.
If @jofemodo wanted to produce the main product with the compute module then we could have a slightly better / more customised solution but I imagine this may not appeal too much, requiring extra effort to create and support the motherboard and distancing the product from us enthusiasts with a Pi. I would love for this to happen, i.e. the official product consists of a board (replacing the all-in-one) which hosts the interfaces and accepts a CM4 whilst everything continues to support the standard Pi4. In fact, it would be nice for a future incarnation of the all-in-one board to do both, i.e. have the CM4 connections and ability to connect to a standard Pi. Ooh! That would be nice. The Kicad files are available for the CM4 development board from which custom designs like this could be adapted. I am starting to like this idea…
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Using https://geppetto.gumstix.com one can try to extend and modify one of their products like this one https://store.gumstix.com/manufacturer/raspberry-pi/cm4-development-board.html
I gave it a try:
On board there is an audio codec (+ 2 lines in, headphone and stereo line out), hdmi, ethernet, dsi connector, 4USB2, 4 headers connected to gpios for encoders (more about that below), and a M2 ssd connector, power is done trough a barrel jack and they are 2 regulators 5V 5A, 3.3V 1.5A
The set up fee of 1999$ will not be applied, see here: https://www.gumstix.com/special-offer
Pro:
- really easy to use,
- you don’t have to do all the detailed design of the pcb (routing, line length matcing for high speed buses)
- Once your design done, you can download a kicad archive with schematic (.sch) and board design (.brd). But it looks like you have to use a kicad nighlty build version … Maybe it’s an Altium EagleCad file as Gumstix seems to belong to Altium
Cons:
- The part choice offered is really small:
- No mpc23017 port expander, there is a i2c TI solution for that but it doesn’t looks well supported by linux and not at all by wiringpi.
- no optocoupler
- The audio codec is a TI TLV320AIC3106 wich has a linux driver but no RPI4 dts file
- most the parts are over priced (the 2x20 pins male header is 14.45 $ !!!)
Note: I’ve edited the post, add a stereo line out, remove my email adress from screenshot
My favourite new kit at the moment would be an encoder & switch set that could connect to a zynth via USB, so a remote panel would be easily implemented.
I want to add a PEZ dispenser.
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There is no need to use a compute module, if what you want is a smaller footprint this is a good starting point https://github.com/okyeron/fates
It uses a normal Rpi 4 and the majority of it’s connectors but breaks out some of them to the back and adds the screen, encoders and DAC/ADC
Maybe there could be a slimmed down version of the dac/adc + zynscreen + midi circuit to get a slim build in one pcb + rpi or maybe 2 pcbs + rpi.
I myself tried this slimming down concept on mine, getting somewhat of a slim solution (the cabling an the midi+extension pcb were the main things i couldn’t get any thinner), and i definitely see a point in doing something like this but still supporting the DIY way.
I was thinking that maybe the midi circuitry could be integrated within zynscreen and maybe make a breakout for the extra boards if you needed them (As to avoid the 40 pin cable as much as possible).
Wiimote integration as an expression controller and/or drum sticks.
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