I have a bare-chip SAMD21g18 in a test socket that I am trying to flash a simple blinking LED example script to. Issue is after burning a bootloader for nano_33_iot, Arduino 0, and the MKR0, connecting to USB via the TX/RX pins Pin 33/PA24 (USB -), and Pin 34/PA25 (USB+)
The Arduino Zero bootloader has been tried as crystalless but still no luck.
Any ideas of fuses we need to change or something special to allow a Windows computer to recognize it after we burn the bootloader?
You ABSOLUTELY MUST have a capacitor on VddCore (~1uF) This is the output filter capacitor for the internal 1.2V regulator that powers the CPU Core.
In addition, you almost certainly also need additional decoupling capacitors on the 3.3V power supply - usually 0.1uF for each set of power pins, and a 10uF capacitor for the overall chip.
See Section 44 "Schematic Checklist" of the datasheet.
If your "test socket" is specific to the SAMD21 chip, it MIGHT have these capacitors built in. But they don't show in your schematic, so ...
@westfw Thank you! I will refer back to the schematic checklist and get these added. I was able to burn the bootloader and it seemed to program/verify fine so I figured I was ok.