They asked about pointers,
storage classes,
diff between char array and char string,
which compiler u r using,
memory segments, malloc, calloc,
bit manipulations,
which controller u used, what processor used in that controller , which architecture it is,
watchdog timer, what is volatile,
type cast, how to cast int to char,
void pointer and why we use it
what is stack why we use that
rs232,rs485
functionpointers, array of function pointers
which debugger u used
linked list