firmware/src/bare/main-nrf52.cpp

#include <assert.h>

static inline void debugger_break(void)
{
    __asm volatile("bkpt #0x01\n\t"
                   "mov pc, lr\n\t");
}

// handle standard gcc assert failures
void __attribute__((noreturn)) __assert_func(const char *file, int line, const char *func, const char *failedexpr)
{
    debugger_break();
}