Re: [avr-gcc-list] Question about gcc preprocessing and port/pin assignments

[Dave Hansen]

From: James Washer <address@hidden>
[...]
> Bingo... with Dave (and others help).. I know have the following, which 
> allows me to work with PORTx, PINx, and DDRx. This allows me to change the 
> assignment of a pin in one place in the code, and have the DDRx change 
> along with it.. Cool
>
>  - jim
>
>
> #include <avr/io.h>
>
> #define DATA1         D, 7
> #define DATA2         C, 3
> #define DATA3         B, 3
>
> #define PINDEF_PORT(a,b)        (PORT##a)
> #define DDR(a,b)        (DDR##a)
> #define PINDEF_PIN(a,b) (b)

You might simplify some of your macros if you change this one to

  #define PINDEF_PIN(a,b)  (1<<(b))

> //Set a pin
> #define SETPIN(pindef)  PINDEF_PORT(pindef) |= (1 << PINDEF_PIN(pindef))

Then this one becomes

  #define SETPIN(pindef)    PINDEF_PORT(pindef) |= PINDEF_PIN(pindef)

> //Clear a pin
> #define CLRPIN(pindef)  PINDEF_PORT(pindef) &= ~(1 << PINDEF_PIN(pindef))

And this one

  #define CLRPIN(pindef)    PINDEF_PORT(pindef) &= ~PINDEF_PIN(pindef)

and so forth...

[...]
> //Read the value of a pin
> #define GETPIN(pindef)  PINDEF_PORT(pindef) & (1 << PINDEF_PIN(pindef))

You'll probably be disappointed with this one.  Try

  #define PINDEF_PINPORT(pindef)   (PIN ## a)
  #define GETPIN(pindef)   PINDEF_PINPORT(pindef) & (1 << 
PINDEF_PIN(pindef))

Regards,
  -=Dave