On Fri, 29 Nov 2013, Neil wrote:

> Okay, so I have used the disassembly window before, but never enough
> to notice that library functions would be broken down there also.
> Neat.  I've been playing with it and whittling down the code to as
> little as possible and I have a new revelation.
>
> The delay functions are not the issue.  I have two versions of code,
> only one of which works, and the difference is a local vs. global
> variable.  If I use the variable locally inside of the main function,
> it stops working.  I have disassemblies of both, and will break it
> down later.  Perhaps someone here can easily catch something I'm doing
> wrong.   This is the code...
>

Hi Neil,

In a previous post you said that in one case the compiler would stop=20
working. This is what attracted my attention. This further info about the=20
global / local problem is also very interesting.

Try changing the name of the global "i" variable to something else,=20
something unique and unused anywhere else. Uncomment out the definition of=
=20
the local "i" variable. Does it still work?

I wonder if the compiler is getting confused and using the address of the=20
global "i" as an offset into the runtime stack.

Regards
Sergio Masci

>
>
> unsigned char i;
>
> void main(void)
> {
> 	unsigned char i;	// <--- Comment this out and the code works
>
> 	OSCCON =3D 0b00010000;	// 1 Mhz internal
> 	OSCCON2 =3D 0b00000000;
> 	OSCTUNE =3D 0b00000000;
> 	TRISA =3D 0b11011111;
> 	TRISB =3D 0;
> 	TRISC =3D 0;
> 	ANSELA =3D 0b00000011;
> 	ANSELB =3D 0;
> 	ANSELC =3D 0;
> 	LATA =3D 0b00000000;
> 	LATB =3D 0;
>
> 	while (1)
> 	{
> 		LATC =3D 0b01010101;	// '0's will turn LED's on.
> 		for (i=3D0; i<250; i++)
> 			Nop();
> 		LATC =3D 0b10101010;	// '0's will turn LED's on.
> 		for (i=3D0; i<250; i++)
> 			Nop();
> 	}
> }	// main()
>
>
>
> Cheers,
> -Neil
--=20
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