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Automatic chicken door time input (low power, simple)
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Amper:
Hi!

Im looking for some random ideas here, no perfect solutions for my problem but just a bit of brainstorming help.

A year ago i built an automatic chicken coop door for my mother. It has to close and open a door every day and lock it reliably. Since its usually quite dirty around and i didnt want to play around i decided to mount two industrial pneumatic cylinders to the swing open door and since i dont want a chicken decapitator its powered by a small 12V air pump rather than a real compressor. The mechanical part works very nice for over a year now but the electronics were just bodged together by lack of time. I used a leftover arduino, and some chinese boards to control the two selenoids and the pump. Since i want it to be operated by everyone intuitively and i dont want to write a manual the adjustment of the "business hours" is currently done by adjusting an external line power timer that tells the arduino to open or close. This obviously sucks big time and im not proud of hacking stuff together like that. Also the continuous power consumption of the mechanical timer, the line relay and the arduino make me dependent on the grid.

Its no big deal power wise but it sucks to have cables laying around in the dirt and also in a wooden house with hay and dust its a significant fire hazard.

Since i have also built a few low power data loggers recently i decided that its time to change this thing. Power will be supplied by a small solar panel on the window and stored in two 400F 2.7V Supercaps (I also dont like batteries that freeze and/or leak when broken). The arduino will be kicked out and be replaced with just the ATM328, the selenoids need quite a bit of power (6W) and will be replaced by a second air pump.  This way only very little standby power is needed (5uA for the micro is all) and the Opening / closing takes only around 100J each day.

What worries me only is the adjustment of the times depending on seasons, weather and other needs. There has to be some way of telling the 328 two daily times  in 24h format when to open and close. The obvious solution would be to add an oled display and an encoder, wake the 328 via pin change interrupt and have a menu appear. But i dont really like this idea for practical reasons of noone wanting to climb a ladder and change settings on a tiny screen. Also i like low tech solutions in these situations.

The next idea was to use bcd coding switches but to put these directly onto the pins of the controller would take 10 pins even if i decided that i dont need minute adjustment. This will not leave open enough for the RTC and control of the door.

Enough blabbering around on my side, do you guys have any nice ideas?

cheers
nsrmagazin:
This is easy, but the cables can not be avoided unless you have a heavy duty battery and you charge it at least every 3 months. Why not pass the cables with a good cable and outside isolation? Its a plastic square tube through which you pass the cables. Its the best solution to me, you don't need to pass them through the ground, it can be through the roof.
mycroft:
How about two pontentiometers for the opening and closing times? Put a hand written scale and it is done.
rhodges:
I was thinking about using a table or equation to adjust the open and close times every day, to follow the day and night cycles. The solar cell might give a useful signal to help this.

I like the suggestion of two pots. They could be for absolute times, or offsets from the internal day and night times.
nsrmagazin:
For absolute times the pots are the best option. You should mark the pot setting so you can use it again afterward.

If you want to do it with the changing of the light, you can use an IR LED with a comparator. You can still add pots to the circuit to make it calibratable.

Here is an example(exclude the white transmitter IR LED, it will be replaced by the day and night sunlight unless something blocks it like a leaf or other).
http://elonics.in/breadboard-projects/infrared-ir-proximity-obstacle-sensor-using-lm-358

With absolute settings(which is better) you need to remove the IR white transmitter LED. Remove the black receiver IR LED and add the input voltage in the place of the black receiver IR LED.

A digital clock with a timer 555 would be an option too. The clock counts 24 hours and on certain hours it does something.

I guess you don't want to go in the dark and check the chiken's door, if its because you are afraid of something its a dog you need.
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