If you leave out the status LED circuits this uses no more than 10 components. It of course leaves out some safety measure that you don't always need, the point is to demonstrate just how little is really necessary to get things going. This is true for many SoMs not just the CM4.
Ok just to be clear. Please don't suffer through making a PCB at home. The idea was to show you that high-speed signals can be ok even in the worst of circumstances, a 2$ PCB will do an infinitely better job than this milled PCB 😄
And as requested here is just the carrier.
Yes the connectors are not super easy to solder, you need magnification and a steady hand but a 30$ stereo-microscope totally does the job here. If you did SMD before and feel ok about it you will have no issue.
Below is a trick to get the alignment right when hand soldering.
What makes these hard is that they are very long. To make this easier align it on one end and tack down just one single pin, you can still rotate it quite a bit. Go to the other side, align, tack down a pin and you are good to go with just drag soldering along the whole thing.
The project is now uploaded to https://hackaday.io/project/175832-minimal-raspberry-pi-cm-4-carrier
and the PCB files to https://github.com/PTS93/Minimal-RPi-CM-4-Carrier
Please keep in mind this is nothing but a quick and dirty demonstration. Especially the routing is far from good and completely optimized for CNC milling, nothing you wanna copy
And do not use that SDcard connector, its horrible to hand solder, its just what I had at hand :)
Most microSD card connectors are much easier to solder with visible pads.
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