Lpc2000

Tom Walsh wrote:

> Ake Hedman, eurosource wrote:
>
> >I have found part of this problem. The GNU compiler translates
> >
> >WDFEED = 0xAA; WDFEED = 0x55;
> >
> >to
> >
> >710 04c4 8E22A0E3         mov    r2, #-536870904
> >711 04c8 5530E0E3         mvn    r3, #85
> >712 04cc 0030C2E5         strb    r3, [r2, #0]
> >713 04d0 8E22A0E3         mov    r2, #-536870904
> >714 04d4 5530A0E3         mov    r3, #85
> >715 04d8 0030C2E5         strb    r3, [r2, #0]
> >
> >
> >i.e. just writing 0x55.    This is done even if compiled with
> >optimization of.
> >
> >Anyone know how to work around this?
> >
> > 
> >
> do you have WDFEED declared as "volatile"?  This tells gcc not to
> optimize out accesses to that memory, that the memory location may
> change between readings (as in the case of an interrupt writing to that
> location).
>
> example:
>
> volatile char * WDFEED;
>
Thanks Tom,

Yes its defined as

#define WDFEED         (*((volatile unsigned char *) 0xE0000008))

forgetting volatile have bite me so many times during the years. 

/Ake


-- 
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Ake Hedman (YAP - Yet Another Programmer)
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