Arduino and SLEEP_MODE_IDLE

Using Arduino Programming Questions
9

It is possible to do much better. But it requires work to get there.

I'm newbie in the electronics and my knowledges are ending with the using of 7805 as 5 volts voltage regulator. I think there is nothing more that I have to do with the arduino. If I have to do something better I have to work on 7805 regulator high power consumption.

I did a little program to measure the WDT overflow period with prescaler set for 8 seconds:

void loop()
{
  if (resetTimeWDT == 0) {
    wdt_reset();
    resetTimeWDT = micros();
  }
  
  if (overflowWDT > 0) {
    Serial.println(overflowWDT - resetTimeWDT);
    
    overflowWDT = 0;
    resetTimeWDT = 0;
  }
}

ISR(WDT_vect)
{
  overflowWDT = micros();
}

Here are some of the results:
8690588
8690084
8689688
8690220
8689876
8689576

So you are right. WDT accuracy is really bad. Maybe I have to calibrate it somehow in each 10 or 30 minutes.