Hey, I figured I'd throw these insturctions together along with part list and some pictures. I just made a dongle for pretty cheap using some open source code, and wanted to share.
Its pretty bare bones, kidna ugly, and has no case. But its cheap and easy. I'll probably try and make something to put it in someday, but I don't have a 3d printer. I've included links to everything on Adafruit and Amazon for other parts. Don't worry, they aren't affilate links =)
Overall, this is pretty cheap and easy to put together. The main parts are from Adafruit, and a few cables/adaptor I already had.
This is an inexpensive (about $10 USD) board, that is about the size of a quarter. It also has a micro usb port and JST for solderless power!
This cheap 2 x coin cell holder has an on/off switch and a JST connection to easily power the Gemma.
These are simply coin cell batteries, they don't need any explaination...
I purchased a 3 pack of these on Amazon for use with an Android phone. They work here as well.
I had this already for plugging my Switch into an external battery pack. You could also use the cable the pro controller comes with.
You probably already have one of these...
The parts I chose were for ease of use. Its extrmely easy to put together!
If it doesn't work, you probably put them in upside down...
I did the first time =)
Plug the battery pack into the Gemma, and make sure both the Gemma and Battery have their power switches turned on. The LED will cycle R-G-B colors with the default software on the Gemma.
Follow this github repo's instructions: https://github.com/noemu/sam-fusee-launcher
The instructions are for a Trinket M0, but they are the same thing, except when you select your device from the Arduino software, you will chose Gemma M0.
You obviously don't need to follow the part about putting the hardware together in the github repo, since it doesn't apply to us.
Its pretty easy
Here's a video of it in action. I was a bit excited that it worked on the first try. I use Auto RCM on my Switch.
I dind't come up with any of this on my own, but was inspired by a few other reddit threads and some comments by others.
Reddit user liocer who mentioned using a Adafruit Gemma M0. I never heard about them, and everyone always talks about the Trinket M0. liocer also linked to the github repo that has the code we use.
Github user Quantumcross who's fork I used for my very first instlattion on the Gemma. Its geared towards an internal trinket, but it works. I ended up using the original repo it was forked from.
Github user atlas44 who created the launcher for an external Trinket M0 dongle. It works for the Gemma as well =)
Everyone who created the tools/payloads from the switch hacking scene