BitwiseOperations
For better understanding how to manipulate single Bits...
/**************************************************************************************************
*
* bitwiseOperations_00
*
* Version: 00 - Mai 2010
* Author: Tom Pawlofsky www.caad.arch.ethz.ch tom-DOT-pawlofsky-AT-arch-DOT-ethz-DOT-ch
*
* Desc: show how to set single bits of a Byte
*
***************************************************************************************************/
/* some nice links
http://www.arduino.cc/playground/Code/BitMath
*/
void setup(){
byte a; // 00000000
byte b;
byte c;
byte d;
// start Serial communication
Serial.begin(9600);
Serial.println("bitwise Examples");
// example how to create 00000100------------------------------------------EXAMPLE-1------------------------------------
Serial.println("create 00000100");
a = B00000100; // use arduino constant
b = (1<<2); // use bitshit - shift 1 by 2 positions to left
c = 4; // use the decimal equivalent of binary 100
bitSet(d,2); // use the bitSet function of arduino, note: the bits are indexed from right to left, 0-based
// bitSet is similar to the sbi() macro you sometimes find if Registers of the microController are accessed
Serial.println(a,BIN);
Serial.println(b,BIN);
Serial.println(c,BIN);
Serial.println(d,BIN);
// example how to combine multiple Bytes to create 10101010----------------EXAMPLE-2------------------------------------
Serial.println("create 10101010");
a = (1<<7) | (1<<5) | (1<<3) | (1<<1); // combining 10000000 , 00100000, 00001000 , 00000010 with bitwise OR
Serial.println(a,BIN);
// example how to modify only 3 places of one Byte-------------------------EXAMPLE-3------------------------------------
// try to change only position 1..3
// create xxxx111x
byte mask; // see also http://www.arduino.cc/en/Tutorial/BitMask
byte modify;
Serial.println("create xxxx101x");
a = B10000011; // 100000 11
b = B10001111; // 1000 1111
c = B10111111; // 10 111111
d = B11111111; // 1 1111111 just some "0-1-grafic"
mask = B00001110;
modify = B00001010; // you can change modify to B0000xxx0 to play with
// clear bit 1..3 with bitwise math using a mask
a &= ~mask; // sets all bit s to 0 that are 1 in mask
// set a equal(=) to the bitwiseAND(&) of old a and bitwiseNOT(~) of mask
//
a |= modify; // combine a bitwiseOR modify
// do it in one line
b = (b & ~mask) | modify;
c = (c & ~mask) | modify;
d = (d & ~mask) | modify;
Serial.println(a,BIN);
Serial.println(b,BIN);
Serial.println(c,BIN);
Serial.println(d,BIN);
}
void loop(){
}