Example for Displaying Binary

Suppose DIP Switch 1 is set to 0xFA.  When PrintSwitch gets called, byVal will be equal to 0xFA.

In your loop, you should print out:

11111010

Or to break it down further:

Bit	Status	Action
7	On	Print a '1'
6	On	Print a '1'
5	On	Print a '1'
4	On	Print a '1'
3	On	Print a '1'
2	Off	Print a '0'
1	On	Print a '1'
0	Off	Print a '0'

Thus, you need to test each bit.  The only way to extract bits from a value is to use bit-wise operations.  What bit-wise operator lets you test to see if bits are on or off?

| OR - Set
^ XOR - Toggle
& AND - Clear/Test

The bit-wise AND (&) allows you to test for individual bits.  Why is this? 

Value & 0 = Always 0
Value & 1 = The same value

In order to test for a bit, you can use the above properties of the AND operator.  For the bit you want to test, AND it with 1 since anything ANDed with a 1 gives back the same thing.  For the bits you don't want to test, AND with a 0 since anything ANDed with a 0 gives a zero.

Think of the bit-wise AND as a filter with the 1's allowing bits through and the 0's forcing the value to zero.  Consider testing for bit 7 to see if it is true or false.  The C code would look something like the following:

if(byVal & 0x80)
{
  /* Bit is on */
}
else
{
  /* Bit is off */
}