The fastest command to read I/O pin

Projects Programming
1

Dear Sir/Madam,

I wonder which is the fastest way to read I/O pin status in arduino board. I know that "PORTX" can set HIGH/LOW on I/O pin faster than "digitalWrite()", so I want to know which is the fastest method to read the I/O pin status?

If i need to read the D6 pin status, the following methods which method is faster? or maybe say in other way is that do "bitRead()" consume lots of time?

Method 1:
byte val = PIND;
val = val & B01000000;

Method 2:
byte val = PIND;
boolean pin_6 = bitRead(val,6);

Thank you very much!!!

Best,
Wave

2

UNO
Example:

byte val = PIND & B01000000; // Read D6 ~120ns

.

3

Be aware you get back 0, or 0x40 from that.
You could use it in a sketch like this:

if ((PIND & 0b01000000) == 0){
// bit was low
}
else {
// bit was high
]
4

Good point.

5

byte val = PIND;
val = val & B01000000;

byte val = PIND;
boolean pin_6 = bitRead(val,6);

byte val = PIND & B01000000; // Read D6 ~120ns

The compiler is pretty smart. Those all produce exactly the same code.