Arduino Interrupts - Claus Kuhnel - Bog

Interrupts are an important option to increase the efficiency of your Arduino code and are typically much underutilized. Interrupts are a mechanism found on all microcontrollers to implement real-time behavior of the device. The interrupt system monitors the status of a pin, a timer, or another module and reacts immediately when an interrupt occurs. This mechanism improves the runtime behavior of software in total. This eBook describes the use of interrupts with the Arduino in detail.