google finds 33.600 entries for "undefined _sbrk"

No, you are not the first one who did not read the documentation and 
checked for a solution using google...

You should read the newlib documentation, to understand the reason and 
possible solution.

After carefully reading this you might look ath this:
http://www.yagarto.de/download/yagarto/syscalls.c

Oliver

hello forum,

I tried to copy a syscall.c from the
newlib documents --> http://sourceware.org/newlib/

          caddr_t sbrk(int incr) {
            extern char _end;    /* Defined by the linker */
            static char *heap_end;
            char *prev_heap_end;

            if (heap_end == 0) {
              heap_end = &_end;
            }
            prev_heap_end = heap_end;
            if (heap_end + incr > stack_ptr) {
              write (1, "Heap and stack collision\n", 25);
              abort ();
            }

            heap_end += incr;
            return (caddr_t) prev_heap_end;
          }

my question
what does the micro do when abort() is called ?
does the micro stop running or does the program crash ?

I dont want my micro board fry - its 50.- US$
once my another program crashed and my micro fried indeed