Re: [avr-gcc-list] Setting pin to high in function instead of main, instructions in main never run?

[Peter Fuhrmann]

> === // Bare minimum start (faulty behavior) ===
>
> #include<avr/io.h>
>
> void turn_on_pb(void);
>
> int main(void)
> {
>         DDRB |= (1<<  PB0);
>         turn_on_pb();
>
>         for (;;) {
>
>         }
>
>         return 0;
> }
>
> void turn_on_pb(void)
> {
>         PORTB |= (1<<  PB0);
> }
>
> --- --- Disassembly start --- ---
>
> 00000000<turn_on_pb>:
>         return 0;
> }
>
> void turn_on_pb(void)
> {
>         PORTB |= (1<<  PB0);
>     0:  28 9a           sbi     0x05, 0 ; 5
> }
>     2:  08 95           ret
>
> 00000004<main>:
>
> void turn_on_pb(void);
>
> int main(void)
> {
>         DDRB |= (1<<  PB0);
>     4:  20 9a           sbi     0x04, 0 ; 4
>         turn_on_pb();
>     6:  0e 94 00 00     call    0       ; 0x0<turn_on_pb>
>     a:  00 c0           rjmp    .+0             ; 0xc<main+0x8>
>
> --- --- Disassembly end --- ---
>
> === \\ Bare minimum end ===

The assembly looks correct. This should work. Maybe the RAM of your AVR 
is faulty so function return doesn't work, or the powersupply is 
unstable. I think this is most likely to be a hardware problem.
Another possibilitty ist that the Stack Pointer isn't set up properly in 
the startup code, so the function can not return.

Could you try another chip or another Board ?

Best Regards,
Peter