Sorry, it’s not available for Arduino Mega, so you can only debug Mega with the RAM breakpoints. For now, the special bootloader is only available for Atmega328, so flash breakpoints can be used only with Arduino boards based on Atmega328 – that is Uno and Nano (both tested and working) and some other variants (which I didn’t test). So that’s why you need to replace the bootloader in your Arduino. But using flash breakpoints requires being able to write to the flash memory which is only possible if you use special bootloader. With flash breakpoints, the location in your program where you insert a breakpoint is replaced by jump to the debugger, so the program runs at normal speed until it hits the breakpoint and stops. If you need the program to run at normal speed before it stops at a breakpoint (for example, to generate some signal) you need to configure the debugger library to use flash breakpoints.

In many cases, this slowing down is not a problem, but sometimes it is.

This is because the debugger must compare the current location of the executed program with table of breakpoint locations to know when to stop the program. With the default configuration of the debugger described in part 2, the debugged program runs much slower than normal.

This part three describes how to replace the standard Arduino bootloader with special bootloader with debugger support which makes the debugging more useful.

Part two shows how to set up VS Code to debug your Arduino program.

Part one deals with setting up the VS Code to build Arduino programs.

This is part three of a three part series of articles on creating and debugging Arduino programs in Visual Studio Code.

Visual studio code debugger step one