Active Peripherals

When peripherals are enabled, they can impact power consumption even if they are not active. Therefore, a developer should make sure that only peripherals in use are enabled. On the Relevant Devices this is intuitive, as all peripherals are disabled by default.

On earlier AVR® devices, the Power Reduction Register (PRR) register has commonly been used to enable or disable peripherals. On the Relevant Devices, this register does not exist. Instead, in the register interface of each peripheral, there is an Enable bit. This, plus a more advanced clock system, with better clock gating, meaning that fewer gates are clocked in an unused clock path, replaces the PRR functionality. It is also more intuitive and user-friendly, as the Enable functionality is placed within the peripheral in question.

The peripheral operation can also be affected by sleep modes. This is discussed in Operating Modes.