Getting Started

Chapter 4: C Types, Operators, and Expressions

Bitwise Operators

Table 5: Bitwise Operators

Operator Name Example Defined
~ Bitwise complement ~x Changes 1 bits to 0 and 0 bits to 1
NOT
& Bitwise AND x&y Bitwise AND of x and y
| Bitwise OR x|y Bitwise OR of x and y
^ Bitwise exclusive OR x^y Bitwise XOR of x and y
<< Left shift x<<2 Bits in x shifted left 2 bit
positions

Right shift x>>3 Bits in x shifted right 3 bit
positions

Bitwise operators are critically important in microcontroller software. They allow
s to do many things in C that can be directly and efficiently translated into
microcontroller machine operations. Keep in mind that these operators work on
bits but are similar enough to the logical operators that you will get confused.
Let’s look at the truth tables for &, |, and ^:

AND OR XOR

0 & 0 = 0 0 | 0 = 0 0 ^ 0 = 0

0 & 1 = 0 0 | 1 = 1 0 ^ 1 = 1

ns on it:

e can starting with 0):

s happening Let’s look at these in binary:

myByte =

u

1 & 0 = 0 1 | 0 = 1 1 ^ 0 = 1

1 & 1 = 1 1 | 1 = 1 1 ^ 1 = 0

Let’s create a variable, myByte and do some bitwise operatio

unsigned char myByte = 0;

W set bit 3 (numbering from the right

myByte = myByte | 0x08;

To see what’

00000000 = 0x00