Bajar velocidad reloj Arduino Mega antes de un Sleep

International Español Software
7

Al parecer, como te digo no se si es por la forma en que la habilito:

attachInterrupt( 0, int_hardw, RISING);
 attachInterrupt( 4, isr_usb, RISING);

mas adelante pongo

#define sei()//activa las interrupciones

y cuando mando a dormir es asi:

void sleepNow()
{
set_sleep_mode(SLEEP_MODE_EXT_STANDBY); // sleep mode is set here
sleep_enable(); // enables the sleep bit in the mcucr register// so sleep is possible. just a safety pin
power_adc_disable();
power_spi_disable();
power_twi_disable();
sleep_mode(); // here the device is actually put to sleep!!// THE PROGRAM CONTINUES FROM HERE AFTER WAKING UP
sleep_disable(); // first thing after waking from sleep:
// disable sleep...
power_adc_enable();
power_spi_enable();
power_twi_enable();
}

y utilizo bibliotecas:
#include <avr/interrupt.h>
#include <avr/power.h>
#include <avr/sleep.h>