This may look like a joyless ripoff of @adafruit's Feather M0 Basic, but I assure you it's not. I redid the pinout entirely to break out as much of the L21's functionality as possible while making it feel familiar: DACs on A0 and A1, all the opamp pins on the analog row, and the L21's special battery backup input on the "free" pin on the bottom. I also reserved pins for an eventual Neopixel and Flash chip; to quote the 'fruit, this board is the “bones” for building future SAM L21 based gadgets.
Had to rework the USB port a lot, as one does, but y’all: that is a bootloader.
