AVR-Chat

On 06/08/2010 22:55, Jeff Blaine wrote:
>
> erikc,
>
> In this project, yes they are together. But that's not always the 
> case. If I can't find a better solution, then I will just set the 
> routeene to work with a 2x4 pair and provide it an "encoder number" 
> which would resolve to A0/A1 for encoder 1, A2/A3 for encoder 2, etc. 
> That's easy. But given I use a rotary in almost everything now, I'm 
> trying to move toward a function which would not have any prespecified 
> index.
>
> Now that I think of it, I suppose I could set it up with arguments 
> PORT, pin A, pin B.
>
> Something like this: char encoder_service(char *avr_port, unsigned 
> char bit_mask_A, unsigned char bit_mask_B)
>
> Which would then be called as (example):
>
> x = encoder_service(&PORTA, 0x01, 0x02);
>
> Think that would work?
>
> 73/jeff/ac0c
> www.ac0c.com
>
> From: erikc
> Sent: Friday, August 06, 2010 7:45 AM
> To: AVR-Chat@yahoogroups.com <mailto:AVR-Chat%40yahoogroups.com>
> Subject: Re: [AVR-Chat] passing an AVR port's bit pointer to to a function
>
> Will the port bits both be on the same port or can they be on
> different ports? If so, it seems to me that the best way to go would
> be to pass the port bits as a bit mask (i.e. pin7 = 0x80 rather than
> pin7 = 7) and do it that way.
>
> erikc
>
> Jeff Blaine wrote:
> > I have an encoder service function that reads a couple of bits from 
> an AVR and increments a counter if a turn was decoded.
> >
> > To make the function generic, I would like to pass the port bits as 
> arguments to the function.
> >
> > Unfortunately, I cannot quite figure out how to pass the port bits 
> to the function. Appreciate advice as to what I'm overlooking...
> >
> > function prototype looks like this:
> >
> > char encoder_service(char *avr_port_bit_A, char *avr_port_bit_B) {
> >
> > }
> >
> > In the main program, I would have something like this to call the 
> function
> >
> > x = char pointer to PORTA0
> > y = char pointer to PORTA1
> >
> > encoder_service( x , y );
> >
> > Using standard C.
> >
> > 73/jeff/ac0c
> > www.ac0c.com
>
> [Non-text portions of this message have been removed]
>
> 
Make sure you define the port as volatile in the function as volatile, 
(gcc lib 1.6.6 p320)

Regards



[Non-text portions of this message have been removed]