https://learn.adafruit.com/debug-arduino-uno-atmega328p-with-adafruit-ch552-qt-py-and-debugwire/introduction
Introduction | Debug Arduino Uno/ATmega328P with Adafruit CH552 QT Py and debugWire | Adafruit...
Using Adafruit CH552 QT Py as debug probe and Arduino IDE 2 to do breakpoint, single stepping, etc on a 8-bit Arduino.
arduino uno
https://onlinedocs.microchip.com/oxy/GUID-8D61C0B9-A97F-4F4D-99F8-1D7424264C2A-en-US-1/GUID-81F9745C-A991-4104-BF2C-E095205A88AC.html
4.5.1.6 Advanced Debugging (AVR JTAG/debugWIRE devices)
I/O Peripherals Most I/O peripherals will continue to run even though the program execution is stopped by a breakpoint. Example: If a breakpoint is reached...
advanced debuggingavrjtagdevices