Spending the birthday playing with this beauty of a controller. ATSAMD51J19 based Adafruit Feather M4. Its a blazingly fast ARM Cortex M4(120MHz) with 512KB flash and built-in 256 bit AES crypto engines and a full USB controller from @microchipmakes. Definitely a huge performance improvement from the SAMD21 series. Real-time processing seems a breeze. Also, you can overclock this controller to 200MHz. Never heard of a microcontroller being overclocked.
Trying to build a custom bootloader for this board with a fresh chip. Seems UF2 Bootloaders from @microsoft will allow you to use it as a USB device and you can use it with Arduino and CircuitPython, MakeCode to program it with the same bootloader are a rage with this one. Reading up a lot on those. @adafruit seems to have done a great job with it. Planning a custom compilation. Anyone having experience compiling UF2 bootloader from source on Windows(https://github.com/microsoft/uf2-samdx1) do reach out. Any help is appreciated. The documentation seems to be sparse. Seems @sparkfun also has a custom bootloader for their Thing Plus series with the same controller.
Thank you again for all the warm wishes for the day. Hope you have a great day ahead.
Edit: Figure out how to do a custom bootloader. Will write a detailed blog about it soon…