问#在Avr 5 (ATmega16)中定义PORTX.x

EN

#include <avr/io.h>

#define PORTC_BIT0_READ()    ((PORTC & _BV(PC0)) >> PC0)
#define WRITE_PORTC_BIT0(x)  (PORTC = (PORTC & ~_BV(PC0)) | ((x) << PC0))

uint8_t a = 1, b;

/* Change bit 0 of PORTC to 1 */
WRITE_PORTC_BIT0(a);

/* Read bit 0 of PORTC in b */   
b = PORTC_BIT0_READ();     

If you want to change the state of bit 6 in a byte you can use _BV(6) which is is equivalent to 0x40. But a lot us prefer the completely STANDARD method and simply write (1<<6) for the same thing or more specifically (1<<<some_bit_name_in_position_6)

For example if I want to set bit 6 in PORTB I'd use:
Code:
PORTB |=  (1 << PB6);

though I guess I could use:
Code:
PORTB |= _BV(6);

or
Code:
PORTB |= _BV(PB6);

But, like I say, personally I'd steer clear of _BV() as it is non standard and non portable. After all it is simply:
Code:
#define _BV(n) (1 << n)

anyway.

Cliff