Doing Logic Analysis To Get Around The CatGenie’s DRM

The CatGenie is an amazing device to watch in action, basically a self-cleaning litter box for cats that even does away with the need to replace the litter. It’s comparable to what the indoor flush toilet is for humans compared to maintaining a composting toilet. However, there is a problem. It uses costly soap cartridges which have to be replaced because an RFID reader and a usage counter prevent you from simply refilling them yourself.

CatGenie and Arduino
CatGenie and Arduino

[David Hamp-Gonsalves] reverse engineered the electronics so that he didn’t have to pay for the cartridges anymore. This has been done before and one of those who did it created a product called the CartridgeGenius, but it’s made and sold as a parttime project and there were none in stock. The cartridges have an RFID tag and another solution which we’ve covered before is to replace the RFID reader board with an Arduino. That’s the solution [David] adopted. So why write this post if this isn’t new?

The RFID reader board communicates with the rest of the CatGenie using I2C and he needed to know what was being transmitted. To do that he learned how to use a cheap logic analyzer to read the signals on the I2C wires, which makes this an interesting story. You can see the logic analyser output on his blog and GitHub repository along with mention of a timing issue he ran into. From what he learned, he wrote up Arduino code which sends the same signals. He and his cat are now sitting pretty.

What he didn’t do is make a video. But the CatGenie really is amazing to watch in action as it goes through its rather complex 30-35 minute process so we found a video of it doing its thing, shown at 3.5x speed, and included that below.  If you’re into that sort of thing.

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Cracking Litter Box DRM

DRM on a specific brand of cat litter box has been cracked. In other news, DRM on cat litter boxes exists.

[Jorge] moved into a new apartment with a feline companion and wanted one of those fancy, auto-cleaning litter boxes. Apparently only one such device exists, the CatGenie. This ‘Rolls Royce of cat litter boxes’ uses little pieces of plastic granules as ‘functional medium’ that are scooped up, cleaned, and returned to use. These granules are washed with a cartridge full of fresh-smelling cleaning solution that comes in a container with an RFID tag. Yep, DRM’ed cat boxes. Welcome to the future.

After cruising around the Internet, [Jorge] found a CatGenie community that has released open source firmware for a litter box and something called a CartridgeGenius, a drop-in replacement for the cartridge tag reader in the litter box. It simulates both the RFID tag and its reader, allowing any robotic litter box owner to select between 120 cycle cartridges, 60 cycle cartridges, a maintenance cartridge, and set the fill level of those cartridges.

Previously, [Jorge] was spending about $350 a year on the solution to clean these plastic granules, so in a few months this CartridgeGenius has already paid for itself.

CatGenie Hacking

[ScottSEA] has six cats. As you can imagine, with six cats, a simple litter box just doesn’t cut it. [ScottSEA] uses the CatGenie. While a self cleaning cat toilet is a technical marvel, it has one major drawback. Much like an ink jet printer, it has disposable cartridges. Those cartridges, just ike some print cartridges, have a built in counter that disables them after so many uses. After adding up the totals for six cats worth of cartridge use, [ScottSEA] started hacking. He has posted directions on how to manually refill them, as well as reset the internal counter using an Arduino.

We suggest that he find a way to harness all that cat power for his home electronics. How many watts could you produce per cat?