Pi-Rex: a bark-activated door opener for dogs

Here’s a weekend project from Dave Hunt for dog owners whose best friends can’t work out whether they want to be inside or outside.

Dave came up with Pi-Rex when the sleep deprivation caused by his new dog barking to be let in or out alternately became too much to bear. She tends to do it at the same time every morning. Dave says: “I could do this with a timer switch and a door strike, but where’s the fun in that?” Indeed, Dave. So instead, he’s made a door that responds to barking. Barking.

You absolutely have to watch the video. I’m not sure whether I enjoyed Dave’s dog impression or his reaction to the door opening the most, but the combined effect had me snorting coffee.

A noise detection circuit tuned to respond to loud dog sounds fires a motor which unlocks the door, and a weight (actually a large bird feeder) and pulley system swings the unlocked door open. Dave says: “I picked up the audio detection circuit in Maplin as a DIY kit for €9.99, the kind of ones where you get all the components and a PCB in a bag, and solder them all together. It took about 30 minutes, but worked perfectly; I could bark, and the LEDs would light as I barked. My family thought I was gone mad when they heard me making dog noises in my workshop.”

Dave, this is magnificent work.

If you want to set up Dave’s dog-operated system in your own house, head over to his website, where all the code you’ll need, some wiring instructions and a parts list are available. He suggests you might like to sample the audio collected and make the door respond to…known barks. I do have one question, Dave: have you trained the dog to shut the door behind herself yet?


MrEngman avatar

What about bark recognition to make sure only Dave’s dog can open the door?

Dave Hunt avatar

LOL @ “a door that responds to barking. Barking.” :)

Graham avatar

Nicely done, but I foresee a few security problems, and you might as well leave the door open.

If this could train dogs to bark less that would be a winner.

svenn avatar

Or just record the dogs bark, that might be just a bit easier :D

MilesBennet avatar

Retinal scanner? :)

David R avatar

Barking Mad? Love it!

Andrew avatar

Hi Dave, that looked like a lot of fun. Can you resist going further?

£15 for a solenoid door latch to help keep doggy warm in the winter. An automatic swing door opener ( as used by wheelchair users ) would be cool, but pricey.

I think you will want to get an RFID detector. For around £20 you can get a little module ( make you own antenna ) that outputs the RFID id string. Now that doggy is chipped she can open the door by standing near it and if you came along with a random RFID card it could say “I’m sorry, Dave. I’m afraid I can’t do that”. ( I didn’t mention the T-shirt Liz )

Jim Manley avatar

Rube Goldberg would be so proud … but he would be even more proud if Dave could figure out how to use more parts! :lol:

I’m not so excited by the prospect of yet-another reason for dogs to bark. Someone just moved into a house around the corner and they leave their large dog alone, sometimes overnight during travel or shift work. The dog is not happy about the situation at all, makes it obvious quite vociferously, and I can’t even imagine what’s happening to the furniture in there. Ruff, indeed :(

hiebel claude avatar

Half done !
This works only once as the door doesn’t close after. I
In any case a good idea :-))

Phill avatar

Wouldn’t it be easier to trade her in for a cat?

Karl avatar

I see a number of security flaws here. Door not properly locked, Burglar says Woof? what happens when the door is shown a piece of Bark? A philosophical quandary.

Simon D avatar

I would use an RFID chip reader.

I did think of a meow activated door for a cat, but you would need accurate voice recognition to correctly control access.

Old catdoors worked with a tuned absorber (RC circuit) on the cat’s collar, but these have been discontinued (I suspect that it’s cos they don’t work so well in the increasingly common UPVC+metal doors). The IR ones are a) expensive, b) cat needs an active collar “magnet” with a battery that dies.

So I would read the dog/cat’s chip. But this does have security implications for a dog version cos a burglar can use it to gain access. A catdoor is generally too small for humans. However I suspect that some families have trained their children to use this method of access.

Graham avatar

A burglar won’t be chipped with the right code, so just make the dog door sturdy.

Rik avatar

His bark is worse than his byte… (sorry)

JohnP avatar

Nicely done, I would use RFID for security reasons, but your setting works great aswell.. nice barking tho hahahahaha

Jim avatar

Excellent example of physical computing, thank I enjoyed it!

Daniel avatar

Haha I very much liked this. Ive been playing around a bit and have set up my pi to turn on my bedroom light and fan from my phone – love the pi

Some Bloke avatar

To all you geniuses saying use RFID – you can’t get one long-range enough to read implanted pet chips. (can put a different style one on his collar, though)

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