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Comment by zevv | Hacker News Reader

I recently made something similar to make use of the unused WWAN M.2 slot in my laptop:

https://i.imgur.com/xGXl4Xt.jpeg

Crack the logitech dongle out of the USB casing and solder on the converter PCB.

I'm very ignorant of hardware, but how does this work? I would have thought that M2 and USB protocols were divergent enough that this would require significant hardware/software emulation in the interface, but this looks to be a simple mapping of some I/O.

M2 is just the physical connector. It can carry PCIe, USB, and SATA.

Could you share PCB files for that? I don't have experience with designing PCBs myself, but with the files I should be able to just order them from PCBWay.

Here are the original kicad files https://github.com/zevv/m2-to-usb

Please do check for yourself if this all makes sense, and I will not take responsibility for any fried laptopts or dongles. Note that the power supply for the dongle is too low: USB is supposed to deliver 5V, but on the M.2 only 3v3 is available. I decided to just give this a try and my Logitech dongle seems to be perfectly happy at this voltage. This might not be the case for others.

This is something that could be rectified (if you pardon the little pun) with a 50 cent 3v3 to 5v TI charge pump if one wanted.

Also make sure that the data lines do not have over-voltages then (level-shifters on these?).

Also some firmware (bios) only accept certain devices on the M2 slots.

NICE! How did you get it to a working physical thing? Any place somebody like me can buy this?

https://www.ebay.com/itm/255949891266

Right, please use this one instead of my crappy design, this PCB seems comes with a DC/DC converter to properly power your dongle with 5V instead of 3V3.

You just send the design files to a PCB manufacturer and receive the boards on your doorstep a few days later. 5 of these PCB's cost me $6 or so.

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