Hot Tub (Balboa) + Home Assistant + ESP32 (M5Stack) = <3

One day I asked a chatbot how easy it would be to make my Balboa hot tub smart. Apparently: quite easy. A quick search turned up an existing GitHub repository ( shomanjk/esp32_balboa_spa ) that controls Balboa spas / hot tub over RS485 with an ESP32, and it supports my spa’s (Iva Idun) control board. Let’s take a step back: why do I want my spa to be smart? Only heat the water when my solar cells…