Owner of Litter Robot 4 frees smart litter box from cloud dependency and shares custom firmware

Joseph DiGiovanni, owner of a Litter Robot 4, decided against using the manufacturer's cloud service to run automations based on his cat's litter box. Instead, he reverse-engineered the device to integrate it directly with Home Assistant.

The Litter Robot 4 relies on an ESP32 microcontroller for external connectivity, which made it possible for DiGiovanni to create a custom firmware. He started with ESPHome, a popular open-source firmware for building smart home devices based on Espressif hardware. The device's architecture proved helpful: a PIC microcontroller handles low-level hardware control and safety features, while the ESP32 is responsible for Wi-Fi and cloud connectivity. This separation allowed DiGiovanni to modify the ESP32's firmware without compromising the mechanical operation or safety mechanisms.

To replicate the communication between the original ESP32 and the PIC microcontroller, DiGiovanni captured and analyzed data traffic with the help of a large language model. He used the findings to build an ESPHome firmware that integrates the Litter Robot 4 neatly with Home Assistant, preserving all core functionality.

The project files are available on Codeberg for anyone interested in tinkering. This is not the first time a cat litter management system has been hacked, and it likely won't be the last. A video demonstration is included after the break.