AVR PORT pins

[Ashutosh Bhatt]

what is the difference between these two instructions

PORTD| = (1<<PD0) and PORTD = (1<<PD0)?

 

also what is it mean by PORTD| = (0<<PD0) and PORTD = (0<<PD0) and PORTD& = ~(1<<PD0) ?

[srinu]

i think u know the truth table of AND & OR logic

 

the same opperaton is going on here..

 

in first two statements..

PORTD |= (1<<PD0 ) and  PORTD = (1<<PD0) both opperations are same

 

but in second statemnt(PORTD = (1<<PD0)), we r dng PD0 as a ONE and remaing all pins are ZERO.

 

in first statemnt (PORTD |= (1<<PD0)), only PD0 as ONE and we r not touching remng PINS..that mean

 

if  PD1=1,

in first statemnt PDO=1 and PD1 also 1

but in second PD0 =1 and PD1 is ZERO.

 

 

and remaing also same…..

 

 

 

 

i hope u undersd…………

[Ashutosh Bhatt]

thanks for the reply

what happens in proteus simulator that i tell u

 

if the following code is written to blink the LED then it blinks fine

 

PORTD = (1<<PD0);

_delay_ms(1000);

PORTD = (0<<PD0); 

 

but if the code is

 

PORTD|= (1<<PD0);

_delay_ms(1000);

PORTD| = (0<<PD0);

 

then it stays on. no blinking

 

but again if the code is changed to

 

PORTD|= (1<<PD0);

_delay_ms(1000);

PORTD& = ~(1<<PD0);

 

led starts blinking

so my questions is why and how?

 

 

[srinu]

ok…

seee here 

PORTD|= (1<<PD0);

_delay_ms(1000);

PORTD| = (0<<PD0);

ur dng OR operation, means applying LOGICAL OR.

that mean dng 1 ORING with 0….

again the result also 1.

 

that is the reason….

 

and one more suggetn is give delay after clearing PD0

means

 

PORTD|= (1<<PD0);

_delay_ms(1000);

PORTD| = (0<<PD0);

_delay_ms(1000);

 

 

 

k?

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