A Tweeting Litter Box


How can you not be interested in a project that uses load cells, Bluetooth, a Raspberry Pi, and Twitter. Even for those of our readers without a cat, [Scott’s] tweeting litter box is worth the read.

Each aspect of this project can be re-purposed for almost any application. The inexpensive load cells, which available from eBay and other retailers, is used to sense when a cat is inside the litter box. Typically sensors like the load cell (that contain a strain gauge) this use a Wheatstone bridge, which is very important for maximizing the sensitivity of resistive sensor. The output then goes to a HX711, which is an ADC specifically built for load cells. A simple alternative would be using an instrumentation amplifier and the built-in ADC of the Arduino. Now, the magic happens. The weight reading is transmitted via an HC-06 Bluetooth module to a Raspberry Pi. Using a simple Perl script, the excreted weight, duration, and the cat’s resulting body weight is then tweeted!

Very nice work! This is a well thought out project that we could see being expanded to recognize the difference between multiple cats (or any other animal that goes inside).

44 thoughts on “A Tweeting Litter Box

  1. Expensive and low effort – bluetooth and an entire raspberry pi dedicated to tweeting? The arduino could handle that.

    If you have the resources, then go for it – but it’s pretty wasteful.

        1. I concede. I hadn’t looked closely at the article before I posted anyway. My bad, I had just woken up.

          I was wrong even if you can get those parts cheap. He is using an arduino AND a RasPi, so my argument was moot from the start.


    1. Be honest with us Nibbler, you requested this build didn’t you? Only a woman would want to know her weight after she has taken a shit, to be able to have the lowest possible wight to brag about.

  2. “Poop Alert: Your roommate just completed a nasty dump of 1258 grams. He currently weighs 103kg. Your roommate spent 23 minutes pooping”

    Not so cute anymore, is it?

  3. So has has anyone registered “scat stats.com” yet?
    for only $1.99 a month registurd users can get the latest scoop
    on pet poos.
    Or you could tie it in with the “I’ve fallen and can’t get up” company.
    as some sort of remote health monitoring service.

    1. Thinking the same thing. I’d figure pee would be easier to discern. I think we can assume the cat has either gone 1 or 2. I don’t know if the do both at once, but usually mine are unary. So, if we know it’s one, then it’s not the other.

      Given the acrid nature of urine from the urea and the ammonia, I think you could somehow sample the air to discern this. pH would rise more for the urine than the feces. I suspect temperature would rise in the box a concomitant amount for either urine or feces, but feces won’t soak into the liter bed, so it might give off more heat to the box area and result in a higher rise. Feces would probably include flatus, so we could use a hydrogen sulfide sensor package to detect this.

      You could also apply heuristics after some manual calibration if you knew typical urine and feces deposit sizes and the time required. I’d expect urination visits are much shorter. The sound is also quite different, with a much higher noise level for urinating (box was in the bedroom years ago, I know). Given we know the mass of the deposit, and the rise in temperature of the box, we could determine the heat energy deposited and the specific heat of the substance as the box cools, but I since feces is mostly water, like urine, these would probably be too close to discern. Finally, some image analysis could really do the trick, but again, cats tend to bury their evidence, so that might be occluded too. Analysis of the feline’s repose during the act could also give a hint, but not much as both poses are very similar.

      So, I ask, any simple ideas for discriminating the two? Perhaps a combination of all of the above with voting and weightings? Or do I just record the entire act on video and send it away to the Amazon Turk API and pay someone $0.05 to tell me what happened?

  4. I’ve just build a prototype of this.. Except I’m integrating it into OpenHAB.. I’d like the system to remind my forgetful girlfriend to empty the litterbox when I’m not home. And I’d also like to graph the cats weight because he is a bit fat.. Was really easy to build. And no problem for a perl newbie (eg. me) to mod the perl to use REST::Client and talk to OpenHAB and ditch the twitterpart..

    Scott; Thanks man :) One more cat on the internet of cats.. :)

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.