hardware debugging for $1.53

https://github.com/dcwbrown/dwire-debug

https://www.aliexpress.com/item/Free-Shipping-FT232RL-FT232-USB-TO-TTL-5V-3-3V-Download-Cable-To-Serial-Adapter-Module/1967861284.html

Looks pretty handy. Much cheaper than an Atmel-ICE. Some assembly required ;) .