Port Manipulation question

Projects Programming
1

Hey, I'm trying to replace some of the digitalWrites in my code with port manipulation for speed reasons.

However, I'm wondering, how do you change the state of 1 pin without effecting the others? For example, if I set 1 pin HIGH, then a few seconds later, I want to set the pin next to it HIGH also, how can I leave the other pin HIGH without having to set it HIGH again?

Regards,
Dan

2

Use bitwise OR to set bits to 1 and bitwise AND to set bits to 0.

PORTB |= 0b00000110;  // Set bits 1 and 2 HIGH
PORTB &= ~0b00001010;  // Set bits 1 and 3 LOW (the '~' does a bitwise inversion changing 0b00001010 to 0b11110101)
3

Here's my thread on the same question:
http://arduino.cc/forum/index.php/topic,93737.0.html

I've been using the digitalWriteFast, which somehow is faster, smaller, and easier than port manipulation.
http://arduino.cc/forum/index.php/topic,93737.0.html

4

John_S:
I've been using the digitalWriteFast, which somehow is faster, smaller, and easier than port manipulation.
http://arduino.cc/forum/index.php/topic,93737.0.html

It's faster and smaller only if your pin numbers are compile-time constants. If your pin number is a variable then it will be the same speed as a regular digitalWrite().