<avr/power.h>: Power Reduction Management

 #include <avr/power.h>

Many AVRs contain a Power Reduction Register (PRR) or Registers (PRRx) that allow you to reduce power consumption by disabling or enabling various on-board peripherals as needed.

There are many macros in this header file that provide an easy interface to enable or disable on-board peripherals to reduce power. See the table below.

Note:

Not all AVR devices have a Power Reduction Register (for example the ATmega128). On those devices without a Power Reduction Register, these macros are not available.

Not all AVR devices contain the same peripherals (for example, the LCD interface), or they will be named differently (for example, USART and USART0). Please consult your device's datasheet, or the header file, to find out which macros are applicable to your device.

Power Macro	Description	Applicable for device
power_adc_enable()	Enable the Analog to Digital Converter module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_adc_disable()	Disable the Analog to Digital Converter module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_lcd_enable()	Enable the LCD module.	ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490
power_lcd_disable().	Disable the LCD module.	ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490
power_psc0_enable()	Enable the Power Stage Controller 0 module.	AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_psc0_disable()	Disable the Power Stage Controller 0 module.	AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_psc1_enable()	Enable the Power Stage Controller 1 module.	AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_psc1_disable()	Disable the Power Stage Controller 1 module.	AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_psc2_enable()	Enable the Power Stage Controller 2 module.	AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_psc2_disable()	Disable the Power Stage Controller 2 module.	AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_spi_enable()	Enable the Serial Peripheral Interface module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168
power_spi_disable()	Disable the Serial Peripheral Interface module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168
power_timer0_enable()	Enable the Timer 0 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM216, AT90PWM316, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_timer0_disable()	Disable the Timer 0 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_timer1_enable()	Enable the Timer 1 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_timer1_disable()	Disable the Timer 1 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_timer2_enable()	Enable the Timer 2 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168
power_timer2_disable()	Disable the Timer 2 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168
power_timer3_enable()	Enable the Timer 3 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287
power_timer3_disable()	Disable the Timer 3 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287
power_timer4_enable()	Enable the Timer 4 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561
power_timer4_disable()	Disable the Timer 4 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561
power_timer5_enable()	Enable the Timer 5 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561
power_timer5_disable()	Disable the Timer 5 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561
power_twi_enable()	Enable the Two Wire Interface module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168
power_twi_disable()	Disable the Two Wire Interface module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168
power_usart_enable()	Enable the USART module.	AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_usart_disable()	Disable the USART module.	AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B
power_usart0_enable()	Enable the USART 0 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168
power_usart0_disable()	Disable the USART 0 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega48, ATmega88, ATmega168
power_usart1_enable()	Enable the USART 1 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, ATmega164P, ATmega324P
power_usart1_disable()	Disable the USART 1 module.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, ATmega164P, ATmega324P
power_usart2_enable()	Enable the USART 2 module.	ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561
power_usart2_disable()	Disable the USART 2 module.	ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561
power_usart3_enable()	Enable the USART 3 module.	ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561
power_usart3_disable()	Disable the USART 3 module.	ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561
power_usb_enable()	Enable the USB module.	AT90USB646, AT90USB647, AT90USB1286, AT90USB1287
power_usb_disable()	Disable the USB module.	AT90USB646, AT90USB647, AT90USB1286, AT90USB1287
power_usi_enable()	Enable the Universal Serial Interface module.	ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_usi_disable()	Disable the Universal Serial Interface module.	ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_vadc_enable()	Enable the Voltage ADC module.	ATmega406
power_vadc_disable()	Disable the Voltage ADC module.	ATmega406
power_all_enable()	Enable all modules.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861
power_all_disable()	Disable all modules.	ATmega640, ATmega1280, ATmega1281, ATmega128RFA1, ATmega2560, ATmega2561, AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, ATmega165, ATmega165P, ATmega325, ATmega3250, ATmega645, ATmega6450, ATmega169, ATmega169P, ATmega329, ATmega3290, ATmega649, ATmega6490, ATmega164P, ATmega324P, ATmega644, ATmega406, ATmega48, ATmega88, ATmega168, ATtiny24, ATtiny44, ATtiny84, ATtiny25, ATtiny45, ATtiny85, ATtiny261, ATtiny461, ATtiny861

Some of the newer AVRs contain a System Clock Prescale Register (CLKPR) that allows you to decrease the system clock frequency and the power consumption when the need for processing power is low. Below are two macros and an enumerated type that can be used to interface to the Clock Prescale Register.

Note:

Not all AVR devices have a Clock Prescale Register. On those devices without a Clock Prescale Register, these macros are not available.

typedef enum
{
    clock_div_1 = 0,
    clock_div_2 = 1,
    clock_div_4 = 2,
    clock_div_8 = 3,
    clock_div_16 = 4,
    clock_div_32 = 5,
    clock_div_64 = 6,
    clock_div_128 = 7,
    clock_div_256 = 8
} clock_div_t;

Clock prescaler setting enumerations.

 clock_prescale_set(x) 

Set the clock prescaler register select bits, selecting a system clock division setting. They type of x is clock_div_t.

 clock_prescale_get() 

Gets and returns the clock prescaler register setting. The return type is clock_div_t.