Milestone day. The HC-01 went from parts on a bench to a working prototype: 52.2% relative humidity and 25.2 °C, read by the sensor, processed by the ESP32, and drawn live on the round display in a gauge-style readout.

The whole chain works — sensor to firmware to screen — and the display module also passed its fit test in the 3D-printed enclosure (last photo).

Still ahead: fan control tuning, closed-loop humidity regulation, final enclosure fit, and field testing in an actual humidor. But today, we celebrate.