Using Sleep Mode

Power consumption has been reduced, but the CPU is still actively doing nothing. To benefit from an interrupt-driven model, the CPU can be put to sleep while waiting for interrupts. In addition, we will power-down all peripherals not used to further reduce power consumption. The code below is included in project low_power_103.

#include<avr/io.h>#include<avr/interrupt.h>#include<avr/sleep.h>#include<avr/power.h>

ISR (TIMER2_OVF_vect){if(PORTB ==0x00){// LED is OFF, turn it on
        PORTB =(1<<5);// Shortened timeout for on cycle
        TCNT2 =0x102;}else{// LED is ON, turn it off
        PORTB =0x00;}}intmain(void){// Disable digital input buffer on ADC pins
    DIDR0 =(1<< ADC5D)|(1<< ADC4D)|(1<< ADC3D)|(1<< ADC2D)|(1<< ADC1D)|(1<< ADC0D);// Disable digital input buffer on Analog comparator pins
    DIDR1 |=(1<< AIN1D)|(1<< AIN0D);// Disable Analog Comparator interrupt
    ACSR &=~(1<< ACIE);// Disable Analog Comparator
    ACSR |=(1<< ACD);// Disable unused peripherals to save power// Disable ADC (ADC must be disabled before shutdown)
    ADCSRA &=~(1<< ADEN);// Shut down the ADCpower_adc_disable();// Disable SPI power_spi_disable();// Disable TWIpower_twi_disable();// Disable the USART 0 modulepower_usart0_disable();// Disable the Timer 1 modulepower_timer1_disable();// Disable the Timer 0 modulepower_timer0_disable();// Change the clock prescaler
    CLKPR =(1<< CLKPCE);// Scale by DIV64
    CLKPR =(1<< CLKPS2)|(1<< CLKPS1)|(0<< CLKPS0);// Port B5 to output
    DDRB =(1<<5);// Timer2 DIV 1024 
    TCCR2B =(1<< CS22)|(1<< CS21)|(1<< CS20);// Overflow interrupt enable
    TIMSK2 =(1<< TOIE2);// Interrupts onsei();while(1){set_sleep_mode(SLEEP_MODE_PWR_SAVE);sleep_mode();}}