Pro Micro USB-C expansion

I took the schematics of the Sparkfun Pro Micro and changed the USB Micro female connector to a USB C male plug here on github. I hope that it would be able to allow others to prototype with arduino on the framework laptop.

Evidently, it’s a couple millimeters longer, so the casing for the expansion card (if made), would need to be extended a few mm outsidethe laptop.

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Another reason why I wanted a USB C pro micro would be to add a dedicated QMK module for the laptop.

Can get this into a real thing of anyone would like. I am willing to make a PCB for this.

I’d love to get a PCB for this, but when I got a quote from PCBway, it came out to be a little over $250 for 5 (assembled). It’s obviously expensive for $50/board, but there’s also a chance that I might have made a mistake somewhere too. ¯\_(ツ)_/¯

Let me do a little bit of magic and I’ll get a PCB ready. A custom PCB that is.


Would you like the DEV-12587 3.3V/8MHz version or the DEV-12640 5V/16MHz version?

I’d go with which ever is cheaper, so it’d be more affordable for everyone.

They are exactly the same price, I can do both but I will do the 5v 16MHz first. On sparkfun’s website

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The schematic is done, would you like the headers on the side of the card or on the inside with pin headers or something else.

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If it’s possible, I’d like to have it retain the same footprint as the pro micro.

So with solder holes essentially. I would prefer having jumpers for ease of use.

I picked up the USB-C Adafruit QT Py RP2040 and I’m hoping with a male to male USB-C adapter that it will fit within the space of an expansion module pretty nicely. With the QT (Adafruit’s mini Stemma/Grove connection) I can hook up to an outside sensor or other devices (QT/Stemma hub?) pretty easily and I’m thinking there might be space to leave the short QT cable tucked back inside when it isn’t in use.

Yep, I could make a rp2040 aswell with a properly designed board so there is no jank at all.

I took a look at the adafruit listing and found this:

Pinout and shape is Seeed Xiao compatible

Someone posted about a module + seeduino xiao here. If you’re looking to get a USB C male to USB C male adapter, it would stick out just so slightly.

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What would your final take on connection method?

Through hole connectors, please

When I do get this made one quick note is J1, the solder pad bypasses the regulator, so if you need 3 volts you would use the output on the headers and if you want 5 volts you connect to J1 as per the product page and But if you want to supply it voltage through the headers it will only output 3 volts.

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Interestingly enough, I missed the USBC branch of the Sparkfun Pro Micro. I’ve updated the Github to use that as a base model for the PCB in the master branch, and moved my previous work into another branch.

That’s all good, as this will be a proper card so that’s all good.

PCB is done! Finishing touches will be done to finalize the design.