The problem is that i need an accurate timer in order to know the time between the last 2 pulses every about 5 minutes.
But if i use an external timer2 using an external 32 KHz crystal i can wakeup and have also the accurate timer2 mills... is this true ?
This pulse sensor must read a LED pulse of my current power meterand then send it via RF every 5 minutes to another arduino base.
Now I don't remember where I read but I remember that tha cpu can sleep but have also the external interrupt active. Is this true ?
Pin change interrupts on PCINT23..0 are detected asynchronously. This implies that these interrupts can be used for waking the part also from sleep modes other than Idle mode.
attachInterrupt(1, onPulse, RISING);
cause of use of internal 8MHz RC clock... it is there a bootloader that can use 8MHz internal clock ?
Note that these techniques only work with the Arduino Duemilanove w/ an ATmega328, not the Arduino Uno (or older Arduino boards w/ an ATmega168).