Hi Clive,
Absolutely, my plan was to open all of this stuff up once I’d gotten over the Kickstarter hurdle. I’m on the final straight to getting the marketing done, last few renderings and then it’s good to go. I’ll post the link once I’m there (a few days at most).
As the for your project, that sounds amazing, I’ve seen Marc’s stuff and it’s really cool. If I can help in any way just shout - as I mentioned above being dicked about by Fiverr was the best thing to have happened, as now designing circuit boards is my new favourite thing! That CM4 carrier board is probably the most complicated one I’ve done, and been procrastinating over the fabrication until it was perfect, but as of Wednesday I’ve bitten the bullet and did it, so middle of next week I’ll be able to test this and if it’s good then you’ll have a working basis in this PCB - but if you wanted to tweak it I can help.
It’s great fun, but can be frustrating, like those CM4/5 mating connectors go in and out of stock at JLC, the ones I have at the moment give 4mm clearance which is why I was able to fit the register shifters needed for the active driver hzeller made, and I did enjoy manually routing these.
The cool thing about the CM boards is that you get everything, not just the standard I2C, GPIO etc but also the USB stuff so it ends up being really compact. The CM4 runs a bit cooler when at rest compared to the PiZ2 in my experience. Also, and while I haven’t tested it yet, the board is compatible with the CM5 as there’s not PCIe involvement.
I also designed a power board that slotted into this carrier board which handled the power path (PSU+BAT), boost (as I was using 4.2v lipo’s), charge, and a mosfet for a jumper to shut the battery off. While I still need to fiddle with that (the boost board is tricking the charger to always be chargin’) you could do something similar, any extra wiring, switch, and your buck convertor could all fit on it and plug right in.
If the CM is the route you want to go down I can definitely help (and definitely provide the KiCad files, and TBH the original is GPLv2 so I’m obliged to do this anyway 
), even designing a low profile curved belt control box to be 3D printed would top this off!
Anyway sorry for the long response, I’m clearly excited about this stuff, I’ll drop the link in a few days to the project and will provide the files\updates when this thing is delivered (the SD card bit scares me, there’s so much that could go wrong with this board!), which had a couple of alterations (picture below, shows the clearance of the mating connectors also, and threw in the picture of the power board that drops into this too). The only additional bits on this carrier are accelerometer, ADC (using that instead of the more expensive lipo fuel gauage), the audio and amplifier chips. Although the accelerometer chip isn’t being fabricated this time around as it’s leadless (which is interesting in itself) which means it needs x-raying, and is more expensive at JLC.
If you’re interested in getting in KiCad there’s three plugins which absolutely blew me away for importing the symbol and footprints, for mapping to JLC components and the autorouting, I can talk about this stuff until the cows come home!
Ross
