He should have used a describing name for the input and bit, like ALARM_POR=
T =

and ALARM_BIT and defined these in a header file to PINB1 and PINB.

This way he could have changed the definition for ALARM_PORT and ALARM_BIT =
at =

one place only if he wanted to use another input pin. The source code would =

also directly tell what he wanted to do.

I don't know the AVR but I take it that as he wrote it, is a general way to =

check for a bit in a port using the predefined names for ports and bits. If =

this is the case I got it wrong from the beginning since he not only didn't =

provide a way to change the port pin for a specific use in one place but al=
so =

didn't use an understandable name that easily can be redefined. =


/Ruben

> Though the code author's not really done anything wrong, since PINB and P=
B1 are
> both defined in the standard header file provided by Atmel, and are stand=
ard
> constants. Arguably he should have used PINB1 instead of PB1 for better c=
larity.
> =

> On 3/7/07, Ruben J=F6nsson <ruben@pp.sbbs.se> wrote:
> >
> > >
> > > The thing is PB1 is a constant indicating pin number, and it was
> > shifting
> > > the 1 PB1 times to the left and then ANDing it to PINB.
> > >
> > > Just a missreading
> > >
> > > THANKS!!
> > >
> >
> > Which proves the fact that in order to write maintainable code it is ve=
ry
> > important to choose a meaningful name for variables and constants.
> >
> > The original author actually did manage half way since he in fact provi=
ded a
> > way to easily change both the port and pin for a function in one place =
- the
> > header file.
> >
> > I would have used macros, though.
> >
> > /Ruben
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> > Ruben J=F6nsson
> > AB Liros Electronic
> > Box 9124, 200 39 Malm=F6, Sweden
> > TEL INT +46 40142078
> > FAX INT +46 40947388
> > ruben@pp.sbbs.se
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> >
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
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> =

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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
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