Bats 'n Gons

Using J-link 

GCC ARM toolchain

-add pullup to 5V

-tie SAMD51 vref to 3.3V for analog audio

The UF2 bootloader is neat in that it exposes a USB filesystem that you can simply drag-and-drop files into from your host OS. Here are some links to resources for building and burning:

Building

https://www.hackster.io/wallarug/uf2-bootloader-creating-custom-boards-c9620c

Burning

Using Atmel Studio (Windows Only)
https://learn.adafruit.com/how-to-program-samd-bootloaders?view=allow-to-program-samd-bootloaders?view=all

Using Command Line (Hopefully Linux, too)

https://forums.adafruit.com/viewtopic.php?f=57&t=142170&p=707151#p707151

Soundboard in 10 minutes

BOM

Github

How to build Circuit Python. Hint: look at Trinket config file to configure external flash.

This is a SAMD51 Cortex M4 with space for a small bat sound (we're testing 512 kB and 1 mB). 

• Sound / speaker
• 2 LEDs
• 4 wire connector for communications with D+, D-, V, GND
• Circuit Python compatible
• Capacitive touch sensor
• Easter eggs