Finally hacked the Switch I've had collecting dust for a couple of years a while ago. Time to do something about having to tether it to the computer every reboot.
The Trinket M0, which I would have preferred due to the lower voltage requirement, was out of stock at my regular electronics supplier due to COVID-19. They still had a few Gemma M0:s, so ordered one of those instead, despite its higher voltage requirement and thus needing two CR2032 batteries. The onboard power switch is nice though. Desoldered the JST power connector to save some space, and designed/3d printed an enclosure with a built in holder for two batteries.
Butchered a couple of USB cables, and soldered together a Micro - C adapter. At some point I'll probably replace the onboard Micro female with a C male, to get rid of the adapter.
Happened to have white filament loaded, so printed the first prototype with it. Everything worked at first try, turned out quite well overall actually, even though I had to measure and guess the physical dimensions, there's no dimensional drawing of the Gemma M0 to be found anywhere... The white plastic allows the LEDs to shine through. At some point I might print it in black, and use pieces of transparent filament as light tubes for the LEDs.
Didn't turn out too shabby if I may say so myself:
As for software, I used
sam-fusee-launcher. Converted the latest Hekate ctcaer mod (5.2.1) using the included binConverter tool, worked perfectly. I'm aware there's more advanced stuff available nowadays, but wanted to keep it simple, only need Hekate anyways.
Edit: did some tests. The Gemma M0 doesn't need the specified 4-6 VDC after all, perhaps it's only needed if you want full functionality with 3.3VDC regulated output etc? 3 VDC seems to be enough for the controller at least. Single battery version of the enclosure printing as I'm writing