A note on interrupts - page 2

We might compare this to "polling" with a difference. In polling, we repeatedly check the bit until it goes high.

For example, suppose we want to read a character from a keyboard. On a traditional system, without using interrupts, we often see code like this:

  do { } until (serial.available)
  c = serial.read

Not only does this waste power, but it ties up the entire system while waiting. The only better solution is to use an interrupt instead. Indeed, this is the entire purpose of interrupts.

On a WIZ, we would do something more like this:

  x <= serial.available
  c <= serial.read

This is almost the same code, except instead of looping over and over until the event occurs, we simply "sleep" until the event occurs. This obviates the need for interrupts. And because a WIZ chip is a chip of *many* WIZes, the system as a whole is unaffected.