confusion with bitwise

Projects Programming
1

Well, I am probably too new to fully comprehend just how confused I really am......
But I cut and paste the following directly from the Arduino bitwise page here: & - Arduino Reference

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.....So if we write PORTD = B00110001; we have made pins 2,3 & 7 HIGH.

....PORTD = PORTD & B00000011; // clear out bits 2 - 7, leave pins 0 and 1 untouched (xx & 11 == xx)

/////

So If I am talking about one specific bit in the collection of eight.....which side do I count from?

thanks.

2

.So if we write PORTD = B00110001; we have made pins 2,3 & 7 HIGH

No, that would be 0, 4 and 5.

3

You always start from the least signifigant bit, so that 2^N tells you the value of the bit. Otherwise, bit zero could be 128, 32768 or more depending on the size of the word.

4

so that 2^N tells you the value of the bit

In a C-rich environment, I prefer to write it 2N.

5

Ah, so that is what "sup" means in the editor. 8^)

6

thanks...

OK , that's what i hoped for so that I didnt think I had completely lost it. They should probably fix that, whoever they are.. XD

7

They should probably fix that, whoever they are..

They" would, if you posted this in the Website and Forum section.

8

OK, I did.

9

Are we confusing pins and bits here?

10

KeithRB:
Are we confusing pins and bits here?

I don't think so. The two statements seem to be counting from opposite ends.