Hardware breakpoints are actually comparators, comparing the current PC with the address in the comparator (when enabled). Hardware breakpoints are the best solution when setting breakpoints. Typically set via the debug probe (using JTAG, SWD, ...). The downside of hardware breakpoints: They are limited. CPUs have only a limited number of hardware breakpoints (comparators). The number of available hardware breakpoints depends on the CPU. ARM 7/9 cores have 2, modern ARM devices (Cortex-M 0,3,4) between 2 and 6,x86 usually 4.