Situation: You want to include a timer interrupt service routine in an assembly language program for an AVR-based Arduino. The program will be written, assembled and uploaded using the Arduino IDE.

"So you are running your void loop() code, where you keep checking forever if some input or signal level or other reading is really necessary.\n", ...

The analog comparator, timer/counter, watchdog timer, TWI, and external interrupts remain active in the ADC noise reduction mode. The Arduino can wake up using an external reset, an external level ...