You may type cast the address of the reset vector (0x0000) to a  pointer and call that from C using the following:

((void (code *) (void)) 0x0000) ();

For example, the following program continuously resets itself.

void reset (void)

{

((void (code *) (void)) 0x0000) ();

}



void main (void)

{

reset ();

}

You should note that the software reset sequence above does not clear the 8051 interrupt system or reset any 8051 peripherals. When the above code is executed inside an interrupt routine, the 8051 blocks subsequent interrupts. Therefore, this sequence cannot be used in interrupt service routines.

The following small assembly  may be called from interrupt routines or from your main program. It works by pushing a return of 0x0000 onto the stack and executing an RETI instruction (to return from interrupt). This clears any interrupt conditions and starts program execution from 0000h.

?PR?RESET  SEGMENT CODE

RSEG ?PR?RESET



; C prototype:  void reset (void);



PUBLIC reset

reset: POP  ACC  ; pop return address

       POP  ACC

       CLR  A    ; push 0 as new

       PUSH ACC  ; return address to stack

       PUSH ACC

       RETI      ; execute return of interrupt



       END

This works well when register bank 0 is selected. If this routine is called and register bank 0 is not selected, the program may not  as expected. You should add the following instruction to the above routine or to the startup code to select register bank 0.

       MOV  PSW, #0