Joseph DiGiovanni replaced the cloud firmware on a Litter Robot 4 with a custom ESPHome build that routes all data locally through Home Assistant, zero manufacturer involvement required.
The hardware architecture made this tractable. The Litter Robot 4 splits responsibility between a PIC microcontroller handling motors and safety logic, and an ESP32 handling WiFi and cloud sync. DiGiovanni left the PIC alone entirely. He sniffed the serial communication between the two chips, fed the captures into an LLM to decode the protocol, then wrote ESPHome firmware that speaks that same protocol. Mechanical function and safety features remain intact. Only the cloud dependency dies.
The full firmware is published on Codeberg. The real reason to read the original: the protocol reverse engineering process, specifically how LLM-assisted data interpretation replaced what would have been hours of manual packet analysis, is the transferable technique here, applicable to any ESP32-plus-controller split architecture you want to liberate from its vendor.
[READ ORIGINAL →]