I'm looking for some advice on starting an arduino project. I have a cat feeder/timer which runs on a very inaccurate analog timer and I want to replace that timer with an arduino. Control will be done using push buttons and a small display.
I have: Experience with arduino. Full-time software engineer (me). A bit of electronics experience (thought unused in the last few years) A soldering station Two hungry cats Two inaccurate cat feeders (see pictures)
The Arduino I could fit a normal arduino in here, but a smaller one would be nice. I'm pretty good with a soldering iron, so a micro would be my first choice if it fits all the other criteria.
The action If you look at the photo's you'll see that the feeder uses a spring-loaded central shaft which rotates to open the next feeding bin. There are 5 feeding bins, and four set times so the opening will move from bin 0 to bin 1 at the first set time. The central shaft is manually wound up and released by moving the red arm. This red arm is pushed by the red movable pins on the timer wheel which is driven by the small and large gear. The gears in turn are driven by an analog clock on the back, running on two AA's. I can see several options for replacing parts of this mechanism:
Replace the central shaft with a motor Pushing against the arm Replacing the clock driving the gears with a motor
The first option might not be optimal as this requires the motor exerting some force to move the top cover. Also, the top cover wont be locked into place, which knowing the cats might have disaster written all over it.
The second option might be doable, but I can't think of an easy way to accomplish this.
The third option seems simplest, just use the entire mechanism and instead of gradually turning the timer gears, do a 90 deg rotation at the set times.
Any advice on this as well as the motor and driving electronics I could use would be greatly appreciated.
The power I want to run this project off some simple low-discharge AA's (eneloops). I envision the arduino being in low power mode most of the time, only waking up on timer/button interrupts. How many AA's would I need to run this project for a month before replacing the battery? If I can easily place a basic 1/2/4 AA caddy into the space freed up by removing one of the cooling elements (rounded rectangle spaces on the inside photo).
Any advice on all of the above would be greatly appreciated :)