Hey..
If I am going with the 1st option
I will probably just power only the atmega via a diode and do
If Vin == 0 then write to eeprom..
what do You think if I use a 1500 mfd capacitor after the diode in parallel to the atmega Vcc then how long will it run..??
The eeprom write will probably take nothing more than 3.3ms time..
Or will I need a higher value capacitor...??