> > Hi all,
> > I have a question about passing the name of a pin as an argument to a
> > function. For example, I have a function driveservo(drivevalue,
servopin)
> > and I might want to pass RA0 as the value for servopin.
> >
> > The thing is, if I declare the function as void drvieservo(int
drivevalue,
> > bit servopin) the compiler throws an error. I am a bit lost as to how to
> > get
> > around this problem. I have tried a few hacks, but feel I am probably
> > missing something here.
> >
> > Can anyone help out a Hi-Tech C newbie?
> >
> > Thanks for any and all help,
> > James Fitzsimons
> >
> > P.S I don't think it should make any difference, but driveservo is
> > declared
> > in a different file (servo.c) than the file it is called from
(motcont.c)
> >
> You cannot pass a 'bit' as an argument in HiTech.  One possible workaround
> is to pass a bitmask which can be OR'd or AND'ed with the port to set or
> clear a bit.
>
> Mike
>

To expand on the idea a bit (no pun intended):
[i use unsigned char below for 8 bit values, as this is more ANSIish,
YMMV depending on your compiler]

void driveservo(int val, unsigned char *port, unsigned char mask)
{
    // to turn on the pin:
    *port |= mask;

    // to turn off the pin
    *port &= ~mask;

    // to test the pin
    if ( *port & mask )
        ...
}

void main()
{
    // Do pin RA5
    driveservo( 123, &PORTA, 1 << 5 );

    // And pin RB3
    driveservo( 456, &PORTB, 1 << 3 );
}

Bob Ammerman
RAm Systems

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