Making a proper adapter board for the “smart” WiFi Rinnai

Making a proper adapter board for the
This is a quick follow-up post to my previous article about converting a Rinnai heater device to a smart device and controlling it with WiFi. Previously, when making the board that connects between the ESP32 and the traces of the Rinnai control panel, I did something that is not per-spec. I was using the ESP32 ...