FridgeCure — ESP32 cure-chamber controller

What it does

Works locally

The ESP32 controls the fridge and heater over its own private Wi-Fi network, even when the home router or internet is unavailable.

Adapts to the chamber

Temperature and humidity control bands learn from real cycles to reduce overshoot and excessive compressor or heater switching.

Includes a dashboard

Monitor readings, learned control bands, duty history, plug state, sensor health, Wi-Fi, and optional Home Assistant connectivity.

The practical chamber concept is inspired by Growtutorials' DIY fridge curing guide. That video is a useful reference for chamber layout, fan placement, and water management.

Open the interactive FridgeCure demo to explore the dashboard and settings without a device.

Safety first

This project combines mains electricity, moisture, refrigeration, and heat. Test the system while you are present before leaving it unattended.

Keep smart plugs, power strips, and mains-voltage adapters outside the fridge.
Never put a mains power strip inside the chamber.
Check the current and wattage rating of every plug and device.
Leave ventilation space around the fridge and keep water away from electronics.

No software installation required

Install FridgeCure from your browser

Use a desktop version of Chrome or Microsoft Edge and a USB data cable. Safari and Firefox do not currently provide the Web Serial support required by the installer.

Loading the firmware installer…

Before connecting

Disconnect the sensor and other peripherals if they interfere with the board's boot pins.
Connect the ESP32 directly to the computer with a known-good USB data cable.
Select the exact board model. ESP32-C6 carrier boards are not interchangeable even though they use the same chip.
Choose Connect and install, select the serial port, and keep the cable connected until verification completes.

If connection fails while the existing firmware keeps printing messages, hold BOOT while choosing Connect and install and selecting the serial port. Release BOOT after chip detection begins. If necessary, keep holding BOOT, briefly press RESET/EN, and retry.

The normal installation preserves the settings storage area. Use Erase the entire flash first only for recovery or a deliberate factory reset.

Hardware

Illustration only: use cable lengths and enclosures appropriate for your chamber.

Parts and approximate cost

Part	Quantity	Approximate price
Small fridge	1	20–100 EUR
Supported ESP32 development board	1	5–15 EUR
SHT41 or SHT31 sensor	1	8–20 EUR
Tasmota smart plug	2	15–25 EUR each
Seedling heat mat	1	20–50 EUR
Small 5 V fan	1	5–15 EUR

Pre-flashed plugs are available from suppliers such as Athom's Tasmota range.

Connect the sensor

Turn off the ESP32 before wiring the sensor. Connect VCC to 3V3, GND to GND, SDA to the board's default SDA pin, and SCL to its default SCL pin.

Board profile	SDA	SCL
ESP32 Dev Module	GPIO 21	GPIO 22
Seeed Studio XIAO ESP32C6	GPIO 22	GPIO 23

Hang the sensor in free air near the middle of the chamber. Keep it away from the cold wall, heat mat, direct fan outlet, and condensation.

Seeed Studio XIAO ESP32C6 wired to an SHT41 sensor — Example XIAO ESP32C6 and SHT41 wiring.

FridgeCure sensor settings with sensor type and I2C pin fields — The sensor type and pins can be changed after installation.

First start

Power the ESP32 after installation.
Connect a phone or computer to the Wi-Fi network FridgeCure using password fridgecure.
Open http://192.168.4.1.
Immediately change both the access-point name and password before normal use.

FridgeCure dashboard showing readings, adaptive control ranges, status buttons, and duty history

Connect to home Wi-Fi

Open the Wi-Fi settings from the dashboard.
Enter the home network name and password.
Select Connect and wait for the connected status.

You can then use the displayed device IP. If the network supports mDNS, http://fridgecure.local may also work.

Configure the Tasmota plugs

Use one plug for the fridge and one for the heat mat. Both plugs should join the ESP32 access point so control continues without the home network.

Change the ESP32 access-point name and password in FridgeCure.
For each Tasmota plug, join its temporary setup Wi-Fi and open http://192.168.4.1.
Configure the plug to use the new FridgeCure access-point credentials.
In FridgeCure, assign the fridge plug under Dehumidifier and the heat-mat plug under Heater.
Use each panel's Toggle button while present to verify the correct physical device switches.

FridgeCure access-point settings — Use unique access-point credentials.

FridgeCure dehumidifier plug settings — Assign the plug that powers the fridge.

FridgeCure heater plug settings — Assign the plug that powers the heat mat.

Choose cautious starting settings

Good targets depend on the material, chamber, and ambient conditions. As an initial supervised test, 58% RH and 20 °C are reasonable example values—not universal curing advice.

The targets are averages rather than fixed switch points. FridgeCure learns a control band around each target and adjusts it after valid operating cycles. Watch the first cycles and confirm that the fridge reduces humidity, the heater raises temperature, the fan stabilizes readings, and the compressor does not short-cycle.

Optional Home Assistant connection

FridgeCure works without Home Assistant. MQTT discovery can add readings, targets, device activity, and sensor health to an existing Home Assistant installation.

Configure an MQTT broker and the MQTT integration in Home Assistant.
Open Home Assistant in FridgeCure.
Enter the broker address, port, username, and password.
Keep the discovery prefix as homeassistant unless the broker uses another prefix.

FridgeCure Home Assistant and MQTT settings

See the Home Assistant MQTT documentation for broker and discovery setup.

Disclaimer

This is an experimental DIY controller, not a certified appliance safety system. You are responsible for electrical safety, food safety, process suitability, and supervision of your equipment.