Okay, so here's my situation. I am working on an automated/selective access cat feeding station (two actually). The access will be controlled by RFID tags and I have that all coded up and such. The automated feeding portion will be controlled by a timer and a servo turning a cylinder releasing food into the bowls. So far my plan goes like this: Every 8 hours the feeder rotates and releases food. The cats who are allowed to eat that food, can eat with no problem, but the other cats get shut down via RFID activated, servo powered food bowl covering and maybe a buzz or something.
At first I planned on doing the timed feeding using millis(). Now I'm having second thoughts. If the power goes out, the feeding would be all wacked.
My question: Would it be better to fashion some sort of back up power for my atmega or just use a real time clock?
I'm open to all manor of suggestions, even if it's not a direct answer to this specific question.
If you want to keep time over long periods an RTC would probably be essential because, even without power failures, millis() is not as accurate as a clock.
You know that the processor in the arduino is not supposed to be used for life support systems.
With that in mind an uninterruptible power supply would be the best I think.
How long do you get power outages?
When they happen in UK they make the national news.
You're right. It almost never happens. I'm probably over-engineering. I just don't want to get it all put together and regret including some functionality. What would you recommend as the best option for backup? Is there a way to use a simple battery pack will only be used only when the normal power is out? If it comes down to making a ups sort of battery system or going the rtc route, I think the latter might be less hassle and cost, no? I also like the ability to have time restrictions if I ever want that in the future. I probably should just get started working on it. School has kept me busy and I guess there's a bit of apprehension about my first project involving this many moving parts.
s there a way to use a simple battery pack will only be used only when the normal power is out?
If your battery is of a lower voltage than the power source then simply put a diode in line with each. Then when the power source drops out the battery will take over.