PORT bit manipulation

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

ATmega168

I have a 3to8 decoder connected to pins 2,3, and 4 on PORTD

How would I change these 3 bits without affecting the others.
In other words, if I wanted to send 5 to the decoder it would look like this.

PORTD INITIAL: 01101101
5 = 00000101

so 5<<2 00010100 and put on PORTD without changing the other pins

PORTD FINAL: 01110101

This was my idea

temp = PORTD;
temp &= 0xE3;
temp |= (5<<2);
PORTD = temp;

/* VISUAL REPRESENTATION

PORTD INITIAL:  01101101
5 put on 2,3,4: 00010100
PORTD FINAL:    01110101
*/

This seems a lil clunky, any better ideas?

2

You can make it look slight less clunky:

PORTD = ((PORTD & ~(7<<2)) | (5<<2));

And then hide it in a macro, but I suspect the code created will be pretty much the same as your sequence...