Power Reduction Register

The Power Reduction Register (PRR) provides a method to stop the clock to individual peripherals to reduce power consumption. When the clock for a peripheral is stopped then:

The current state of the peripheral is frozen.
The associated registers can not be read or written.
Resources used by the peripheral will remain occupied.

The peripheral should in most cases be disabled before stopping the clock. Clearing the PRR bit wakes up the peripheral and puts it in the same state as before shutdown.

Peripheral module shutdown can be used in Idle mode and Active mode to significantly reduce the overall power consumption. In all other sleep modes, the clock is already stopped.

8-bit AVR Microcontroller

Power Reduction Register