[avr-chat] Really dumb question about port IO

[Matt.VanDeWerken]

Hi all:

Port IO has been covered a million times on this list, but I am having a
really basic prolem with it.

I am trying to read the value of a port pin on a mega128, using the
following syntax:

    while( (PORT_PWRGOOD & (_BV(PIN_PWRGOOD))) == 0) {
      if(++i>PWR_TIMEOUT) {return digpower = PWR_OFF;}
    }
    return digpower = PWR_ON;

But the function always returns PWR_OFF, even though the pin in question
has been raised. I have checked and double-checked the #define
PIN_PWRGOOD and PORT_PWRGOOD values (they are PORTB and PINB6
respectively, if it matters).  I don't believe I've set the SFR to
enable the alternative function of the pin, either, and the timeout
value is huge (something like a couple of seconds, well after the pin
has gone high).

I must have missed something really basic, surely?

Cheers,
Matthew van de Werken - Electronics Engineer
CSIRO E&M - Rock Mass Characterisation - 1 Technology Court - Pullenvale
- 4069
p: (07) 3327 4142 * f: (07) 3327 4455 * e: address@hidden
"We do not inherit the earth from our ancestors, we borrow it from our
children." 
-- Native American Proverb