Each of the pins on the AVR may have multiple functions. For example, pin D0 and D1 are able to serve as receive and transmit pins for serial port one, respectively. Similarly, a number of pins on the AVR are able to transmit interrupt requests to the CPU when they receive a particular signal. How to implement this functionality is shown below.
| Register Name | Purpose of Register |
|---|---|
| PCICR | Pin Change Interrupt Control Register (Enable interrupts for a particular set of PCINT ports) |
| PCIFR | Pin Change Interrupt Flag Register (When a logic change triggers an interrupt on a particular PCINT pin, the corresponding flag will be set) |
| PCMSK0 | Pin Change Mask Register (Select whether interrupts are enabled on a particular PCINT pin) |