RFID pet feeder

If you have two cats and one of them is on a diet but the other needs free food, you can build a feeder with RFID capability that only opens for the cat that needs free access. The free-food cat wears a collar with an RFID tag.  

Features:
- An old CD-rom player is used as a sliding door
- Timer-controlled open duration
- Proximity sensor (Sharp GP2D120) prevents door from closing while the cat is eating
- Sensors detect whether the door is fully opened/closed. 
- Automatic/manual mode switch (on manual it opens with a pushbutton)
- Arduino controlled

On the downside:
- Mine was made out of cardboard so it is easily broken into by smart/strong animals. One could use a stronger material and add a servo that slides a bar into the door to lock it into place. 
- It doesn't hold a lot of food. 

The first version (shown in the video) used an ID-20 (ID Innovations), which worked, but the range was limited. The cat's tag sometimes hangs on the side, so it did not always activate the reader even when he was in the exact same place every time. Not that big a deal because the cat usually just tried from different angles, but my latest version (shown in the photograph) uses a SEEED studio RDM630 RF-reader with a self-made circular antenna. This antenna is large enough that the cat can poke his head through, which works 100% of the time. The antenna is described in step 7.

Little Cat Toos demonstrates cat feeder from champenoise on Vimeo.
The video shows the first version with the ID-20 as the reader.

Step 1: Materials

- A working CD player tray mechanism+motor from an old cd-rom player
- Sharp GP2D120 Proximity sensor
- 125KHz RFID reader (e.g. ID-innovations ID-20, SEEED studio RDM630, Parallax)
- 1.25" diameter 125KHz RFID tag (or as large as can be worn comfortably on the animal's collar. Tag size influences read range. Bigger is better in most cases)
- Arduino Duemilanove
- 1 adafruit motorshield
- 3 Pushbuttons
- 1 Toggle Switch
- 5  100-220Ω Resistors
- 4  10kΩ Resistors
- 1 Red LED
- 1 Green LED
- The material for the enclosure (such as cardboard, wood or plastic)

Comments

[Dave Kruschke]

Antenna resonance details are pretty important, more so than, say, the thickness of the wire used for the coil. Please see http://www.instructables.com/id/RFID-Reader-Detector-Easy-to-Build (RFID in Instructables) and you will notice a RFID detector here with an LED that uses both a coil AND a capacitor that matches 125 kHz. The LED on this detector lights at the farthest distance from the RFID reader when the coil and capacitor resonate at the frequency of 125 kHz. Roughly speaking, my handwound coil of about 300 uH with about .005 uF of capacitors in parallel with the coil resulted in the best lighting of the LED at a distance of about 4+ inches and mostly meets the requirements of the formula; freq = 1000 divided by (2 times pi times the square root of L times C) where freq in in kHz, C is in uF and L is in uH. I believe that using a capacitor in parallel with the antenna coil is pretty common practice. The wound coil is "fine tuned" by capacitors hooked up in parallel with the coil...
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[lesizz]

I have just finished building my own version of this project. First of all, the following observations:
-Having built this I can appreciate the extensive work landmanr did in developing the feeder.
-I used this project to break myself into learning about and using the Arduino. Having gone through this, I do not recommend this as a project this complex for a first-time Arduino project. Better to start with something simpler to break yourself in. Or, be prepared to take the time with this project to learn the ins and outs of the Arduino.
-Landmar was very helpful in answering a bunch of questions for me. If you decide on this project and you run into obstacles feel free to ask me for help as well as landmar.
-The RDM6300 RFID reader has been discontinued. I am using the ID-20.
-Other posts in this forum refer to a cat door and a cat feeder in the design stage that work with the cat's implanted RFID chip. When I can find out just how that is done, I will probably upgrade my feeder to do that.

The following link goes to pictures of my feeder. Being the nerd that I am I like stuff with flashing LED's, so incorporated several LEDs that glow to indicate various functions.
http://photobucket.com/lxb_catfeeder

If you saw the pictures, I'm sure it isn't lost on you that my unit is boxy and mechanical looking. This is the kind of thing my mother would not let me keep in the house when I was a teenager. This, as opposed to landmar's unit, which is smaller and decorated with designs.

I am presently in the cat-training stage. I will post a video of the feeder in action when it is in full-swing.

Regarding the indicator lights: My background is in electronics, and I have just started learning about writing sketches for the Arduino family. Thererfore I used electronic means to implement the LEDs instead of coding, which would have been a simpler, more elegant solution. But it is what it is. With that expalined, the next link takes you to a shot of the schematic of my unit.
http://i163.photobucket.com/albums/t306/lesiz/Cattronic.jpg

The picture is not large enough to show much detail. I can send a full-size copy if anyone would like. Send me a message from this site.

Like I said, at our house we are in the training stage. The cat without the RFID tag succeeded in breaking into the unit, so I had to reinforce it. The cat with the tag acts very suspicious of the thing. I'm not sure if it's me training the cats or them training me, I'm confident that we soon will be living in harmony with this machine.

[jaxworld]

Great idea, but I have twin Egyptian cats (named Coco and Chanel by my fashionista G'f), and they would rip that apart in about 3 seconds......had to put child locks on the fridge door coz they'd open it.
They get into cupboards above the kitchen surface and we've never caught how they do that...............BUT.....the reason for the child locks was they could get IN to the fridge, but not get out.
So after mild frostbite twice we had to come up with something that they couldn't reach.
But they can destroy anything with food in it that isn't made of steel!!! One nearly drowned in our 5ft high hexagonal fish tank, got in, couldn't get out. Now has four velcro strips coz two they could work.....
We live with Ninja cats!
Had a timed feeder......had to upgrade the motor and lock and put a couple of tiles on it coz they worked it out in 48hrs!
Don't have children,but have trigger locks on my guns for the same reasons!!!
Anyone who could come up with an ARMOURED feeder PLEASE inform!!!
I wouldn't trust them with a frag grenade!!! Never seen two team cats like it, I'm ex-mil and if they were human would love them as part of a 4 man team!!!
Solutions welcome!
Armoured, timed, cat feeder wanted!!! One week good as could put blue freezer packs beneath!

[wizodd0]

It's certainly doable, though likely to be moderately expensive if it's to be truly durable and reliable (and you want reliable, an armored lid could decapitate an animal--or leave them trapped!)

Did you put child-locks on the cupboards to?

I'd keep them from grenades too! They would have the in pulled in a matter of hours at most.

Drop me a line at my handle here -0 g mail & we can discuss it.

[v4l]

Hi, that's a really cool project, totally useful for my cats :)
Would it be feasible to replace the Arduino Duemilanove with an Arduino Uno?

[landmanr]

Yes, it's most likely no big deal

[tlshea]

Hello,
I realize this is the instructables.com site and the idea is to do it myself, but I am a desperate woman in need of something like this now (before my cats make me crazier). Is there anything commercial that performs this?
I do salute your inventiveness and everyone's successful modifications.
Thank you for any insight.

[Caseyjmc]

Yes! MeowSpace www.meowspace.biz

[gcresse]

I just ordered this ID Bowl from https://www.idbowl.com/ and it seems to be exactly what a person needs to keep one cat from eating the other cat's food. It hasn't arrived yet, but hopefully it works as well as on the video.

[landmanr]

That's pretty neat! The only downside I see from that design is that it utilizes infrared, so the tag will have a little battery which I could run out of power.

[gcresse]

Yeah, I also ordered an extra battery. We'll see how happy I am with it after I've used it for a while.

[bobbi0126]

Hi gcresse. Did you have success with the id bowl? I'm looking at buying three sets and I haven't found any other reviews.

[bunner_bob]

We have an ID bowl and have been disappointed so far. The bowl is fairly noisy when it opens and closes, so our regular cats are a bit scared of it (while the fat one just comes running whenever he hears it). The IR tags seem to be prone to failing when they get wet (though they seem to resume working when they dry out), which means when the cat drinks out of a bowl it can kill the tags. The triggering is somewhat inconsistent, depending on what angle the cat approaches at. And, it tried to close on one cat's head, I think because they were eating from an angle. The first one we got had a tendency to "bounce" a few times when manually switched off (it opens when switched off). The replacement was a lot noisier and kind of stuck mid-opening, releasing with a "clack" (again, cats didn't appreciate). Waiting on replacement #2 now. This is the "first infrared pet feeder" - I'm thinking maybe when the design evolves to the third or fourth (and build quality improves) we'll get the one that actually works. And I think RFID is probably a better way to go.

[bobbi0126]

Thanks for the feedback Bob! I'll keep searching for a solution to the #1 dog on a diet, #2 blind dog eating cats food, and poor cat searching for left-overs since the dogs eat everything . ;)

[landmanr]

Hmm, not that I know. There is a host of electronic pet doors available, so if you have a larger space to put the food in you could use such a door to control access. Just an idea.
http://www.solopetdoors.com/home.htm
http://www.petsafe.net/Products/Doors.aspx
http://www.petdoors.com/electronic-pet-doors.html

[Caseyjmc]

We created another solution using polycarbonate plastic and a locking pet door. Several of our friends asked us to build one for them, and then their friends wanted one too. Little by little, we improved this, and added some bells and whistles. Now, we sell it online. It's called MeowSpace® www.meowspace.biz.

[solaralternatives]

For a single cat, wouldn't a magnet/switch combo be a much more elegant and inexpensive solution, eliminating the arduino circuit? (all other cats/animals in the home simply wouldn't have the magnet, so voila, no access!)

[landmanr]

Great idea, although magnets don't typically have a lot of range. One could train the cat to do it exactly right, but the magnet would not always be hanging straight down so perhaps with several magnets around the collar.

[solaralternatives]

I was thinking neodynium.. and a coil detector

[landmanr]

That would be pretty neat

[solaralternatives]

Instead of arduino, the magnet induces an electric pulse in the coil, which opens the door concealing the food. When the cat leaves, another pulse of electrical current is induced, which closes the door. Thus all you need is a very simple flip-flop IC circuit, even ancient TTL circuits would work.

[lesizz]

I've having a problem reading the schematic for the Auto/Manual switch. It's posted as a thumbnail and I can't read it. Could you either describe the connections or send me a full size picture? I'd appreciate it; Kitten Kaboodle would appreciate it:

[landmanr]

I have attached an image to this reply. See if that works..

[lesizz]

Works! Thanks, I appreciate your help.

[dexerit]

This is what I'd like to do but with implanted RFID tags...:
http://www.czamd4.com/pages/video.html

[lesizz]

The implanted tag idea IS doable, as there is a commercial product on the market that does just that -- it senses the vet-implanted rfid transponder. Check it out. I'm sure that you or someone else will come up with an upgrade to make this project implanted-tag friendly.
http://www.moorepet.com/SureFlap-Cat-Door-s/475.htm

[lesizz]

Replying to my own comment:
I just want to add important notes regarding safety:
Cat collars are dangerous, as cats have been known to be strangled when the collar catches on something. Fortunately there are snap-away collars available that will un-snap if the cat gets caught on something. Available in pet stores.

Another safety note: DO NOT depend on this or any other mechanical device to feed your catters when you're away for an extended period of time. Mechanical/electrical devices can and do fail, leaving the cat with nothing to eat.

Really cool project. I have some expired drives and will soon use one to build this project.

[dexerit]

Very nice job man!

Do you think the RFID implanted in the dog/cat 's neck will work?

[yoyology]

Great idea, great Instructable. Almost makes me want to get a cat. Almost.

[insuranceman1]

I'd bring a cat into my home just so I could show off this carazy device to my friends.

[captain Jack]

indeed.
i wonder if this would work for a turtle?

[hsjade1]

I want to build this but new to RF. Was wondering do u have an image of all parts used

[fuzzydale]

This can be used to control entry on a Cat or Dog Door"

NOTE: There may be some changes and improvements coming.
However this circuit does work and you can build it as shown.


The PCB Shown below is Available from me, or make it yourself.
It Measures 2.75" by 1.1"

This circuit uses one tuned coil for on the door and just a single wire loop
on the animals collar.

When the two coils come close together, it produces a signal that can cause
a an LED to light and also trips a solenoid to unlock the door so it can open.
Since all these doors are somewhat different, I leave The Solenoid and Mechanical
Parts of this design for you to figure out.

The Main Advantage of this unit is it does Not Require any Battery on the
animal, as is the case with most store bought devices for this purpose.

--------------------------------------------------------------------------------

The Single turn coil can be joined with plugs so it can be removed easly.
But if the plug comes apart or has a poor connection, the door won't open.
So Better yet, make it Just Barely big enough to slip over the animals head,
and Solder it to make a solid loop, than tape it to the animals collar.
And the Larger the diameter of this coil, the Greater the Sensivity will be.

Also Important, the Cat or Dog door and the surroundings "Can't contain any
large pieces of metal".
(This circuit is also a Metal Detector and This detector see's the Single Loop
of wire as a solid piece of metal.)

Additionally, the coil on the door needs to be mounted in such a way that the coil
on the animal can actually get almost inside the coil on the door.
Possibly a Round or Rectangular Extension, outward from the door will be
needed to accomplish this.

Either way, the coil on the door will probably need to be mounted a few
inches from the door.

Ideally the coil on the door will have an inductance of about 150 uH.
My Inductance calculator can determine this for a Round Coil.

http://www3.telus.net/chemelec/Projects/Cat-Dog/Cat-Dog.htm

[tinker234]

boy my cats would love this yours looks like my cat lunna

[musick7]

Hey thats pretty Slick!

Trying to find a Clever way to do this with Two Cats. One Fat the other always Hungry

[SolomonsJim]

I'm in the same predicament. I'm thinking about modifying this somewhat so that it is capable of responding to two different RFIDs: i.e. when my skinny cat who rarely gets to eat his own food come to the station, the gate will open right away, but when his older, much fatter sister pushes him aside it will read her RFID tag and slam the gate shut. Hmm...I'll have to think about this.

[landmanr]

You can totally do that. You need to modify the code a little bit. Get two tags, figure out what the code for each one of them is (by holding them in front of the reader and monitor serial output), then put each code in an array, and when rfid() gets a tag you check the values against the stored codes. Make rfid() return a 1 if it's tag A, a 2 if it's tag B (and 0 if there is nothing). If it is tag B, you close the door.

I haven't tried it, but I suppose you would have to add something like this to rfid():

int tag1[5] = {2E, 0, CA, EB, 81};
int tag2[5] = {2E, 0, CA, EB, 80};

result=0;count1=0;count2=0;
for (i=0; i<5; i++) {
if (code[i] != tag1[i])
count1+=1;
}
if(count1==5)
result=1;
if(count2==5)
result=2;


And then anytime you're in a timer loop that the door is kept open, check the reader once in a while and if the result==2, you say MoveDoor(CLOSE);

[landmanr]

I have put this feature in a new Instructable, an RFID cat door. The final code for that has the modified function rfid(). It returns a 1 for tag1, a 2 for tag2 and a 0 if neither. Don't try the code I suggested previously, it won't work.

http://www.instructables.com/id/RFID-cat-door/

[jensah]

Could you please attach it as a text file, since this is totally unreadable :(

[landmanr]

You can now download the code directly from here:
http://www.writtensound.com/arduino/cat_feeder.htm
hopefully that helps