Redundant calls to digitalWrite()

Projects Programming
1

If I make a redundant call to digitalWrite() does it have any effect on the output? For example:

while(true)
  digitalWrite(pinNum, HIGH);

while(true)
  if (digitalRead(pinNum) != HIGH)
    digitalWrite(pinNum, HIGH);

Electrically, is there a difference between these two code snippets? For example, does the output waver or stutter at all when the digitalWrite is called?

2

joshuabardwell:
If I make a redundant call to digitalWrite() does it have any effect on the output?

No.

Electrically, is there a difference between these two code snippets?

No.

For example, does the output waver or stutter at all when the digitalWrite is called?

No.

3

Ok, thanks.

4

and if the pin is an input? ]:slight_smile:

5

robtillaart:
and if the pin is an input? ]:slight_smile:

DigitalWrite to an input pin enables or disables the pullup resistor.

6

but this line makes it conditional

  • if (digitalRead(pinNum) != HIGH) ...

so electrical there could be a difference

7

robtillaart:
but this line makes it conditional

  • if (digitalRead(pinNum) != HIGH) ...

so electrical there could be a difference

This was the point of the original question, though. And the answer is that setting an I/O pin to the same state that it has already been set to does not make any difference apart from using a few CPU cycles.