The CM4 to CM3 carrier board is pretty generic, mapping out the bare minimum needed for a CM3.
Would it be possible to redesign the carrier to bring the PCIe lane at the very least to the edge of the board. As I am typing this, I see it has been considered before, without any commentary from ClockworkPi. Another example exists with the MNT Reform CM4 to SODIMM carrier.
Cheers
Anjin
There are several lines of thought with respect to this scattered several places on the board. Itās very frustrating to have so much ātrappedā.
A new carrier board wonāt really fix anything for the IO. To take advantage of the CM4 or future CM5 youād need a new main board.
If the carrier simply brought the PCIe lane to the edge of the carrier, there is plenty of room in the box to add some extras.
A PCIe slot on a carrier board alone would be to big to fit, the width of a PCIe connector is 8.8mm so wouldnāt fit between the main board and the back case
And edge connected ribbon cable would be just fine. Like so many other things, including pi5. An example from another product:
Well it sound like you know what youāre doing, make new carrier board then.
Interesting deduction. If I had the experience with PCB design, why would I ask for assistance? I did find quite a few services that promised to allow ādrag and drop CM4 board design!ā But to no avail. Upverter delivers a populated finished board - not just a PCB! | Gumstix, Inc. | Gumstix, Inc.
In fact, Gumstix said they already solved this very problem, and had released all designs open source. But nopeā¦ GitHub - gumstix/PKG900000001454: PKG900000001454
However, I might note here that asking is my way of learning, hoping the advice and guidance of others might enrich my understanding.
Cheers
Anjin
My personal thought on this, and Iāve started trying to design my own board but itās slow because I donāt fully know what Iām doing, is this. Donāt bother breaking out the PCIe to go out for anything since thereās very little space to put in there. Instead hook it up to a USB controller chip of some kind (only needs to be USB 2.0) and route that to where the existing USB is hooked up to the main board. Then take the native USB and route it instead to the OTHER usb lines on the sodimm side, that are already routed out to the USB-C connector, giving us two USB ports on the console externally, and also allowing us to use the USB-C port in āgadgetā mode so we could even use the u-console as a usb device to some other host.
It should also then be possible to fit some right angle headers on the board to give an internal usb port or two for adding devices, which I think might be more useful than direct PCIe.
Along with that it looks like thereās some companies out there that use a flat-flex cable to RJ45 to add ethernet in other devices, so maybe possible to break out the built in ethernet to a port we can dremel into the side of the console down by the battery, similar to how some people have done with USB ethernet ports here on the forum.