I am looking to design an AVR based circuit* that needs to run for a long time, ideally months, from batteries (with possibly solar trickle charge). From some research it looks like it is possible to put the AVR into a fairly deep sleep where it runs on uA however I need it to wake up periodically.
Given that waking up the AVR is achieved by an interrupt is there a real time clock chip or circuit that can do this from whilst using minimal current? I've done a lot of googling but can't seem to find anything.
*the circuit is a tipping bucket rain gauge that will be left in a remote location and hopefully only serviced once every few months. Obviously the tipping bucket can be used to wake up the AVR on first tip. But I would also like it to wake up say every hour to read the temperature and possibly also once a day to send data back via GPRS
Given that waking up the AVR is achieved by an interrupt is there a real time clock chip or circuit that can do this from whilst using minimal current? I've done a lot of googling but can't seem to find anything.
*the circuit is a tipping bucket rain gauge that will be left in a remote location and hopefully only serviced once every few months. Obviously the tipping bucket can be used to wake up the AVR on first tip. But I would also like it to wake up say every hour to read the temperature and possibly also once a day to send data back via GPRS