A common business practice for companies with questionable ethics is to sell you a product at a reasonable price, and then charge you inflated prices for the required consumables. It’s usually referred to as the razor-and-blades business model, because razor replacements are notoriously overpriced. But, inkjet printer-style business models are even more nefarious, because they use technology to make the product unusable until you buy replacement cartridges. That’s the case with the Cat Genie automated litter box, but David Hamp-Gonsalves has reverse-engineered a solution.
The Cat Genie has a soap cartridge, and like an inkjet cartridge it’s “smart” and knows when it’s low — or at least counts cycles. It’s disguised as a feature that helpfully notifies you when it’s time to replace the soap cartridge, but the Cat Genie will stop working until you do. It’s like if your razor fell apart after a pre-defined number of uses. Those smart cartridges are glorified bottles of soap, but cost a ridiculous $20 per replacement. The “smart” part of the cartridge is an RFID system that prevents you from simply refilling the bottle, and stops potential competitors from selling replacements at a more reasonable price.
Hamp-Gonsalves came up with a clever workaround that altogether replaces the RFID reader built into the Cat Genie. The original system looks at the RFID reader via I2C to determine if there is an OEM smart cartridge loaded, and if that cartridge is full. This solution replaces the RFID reader with an Arduino that’s programmed to send the I2C signals that the Cat Genie expects to see when the smart cartridge is full — allowing you to use a refilled cartridge or none at all. You can buy an Arduino clone for a fraction of the cost of a replacement Cat Genie smart cartridge, so this will save you money from the very first replacement.