Arduino avr-stub debugging

The flash memory is overwritten often when debugging with flash

breakpoints. The flash memory in the Atmel AVR MCUs used in Arduino

should survive about 10 thousand rewrites. When breakpoint is

inserted or removed, part of the memory needs to be rewritten.

To make things worse breakpoints are inserted and removed not only

when you actually insert/remove a breakpoint in the IDE but also

automatically when you continue from a breakpoint (the original

instruction needs to be restored and executed) and also sometimes

when you step through the code the debugger will insert temporary

breakpoint, for example to stop the program after stepping over

a function.

In worst case you, you can expect one write to flash memory for

each step/continue click you do in the IDE. This seems scary but

it is still usable and similar to using the debugWIRE hardware

on-chip debugger module.