Define Busy waiting

"Busy waiting" is the act of actively waiting for some condition to change.

In programming microcontrollers, one might want to wait for a pin to become high or low before continuing with the program.

A "busy waiting loop" in C would look like this:

...

while(PIN1 != HIGH)

;

...

This essentially does nothing but check the value of "PIN1" time after time, waiting for it to become "HIGH".

Now, if PIN1 were to become "HIGH", the processor "breaks out" of this busy-waiting loop and continues with the program.