30 minute DIY ESP32 temperature and humidity sensor for Home Assistant Autodiscovery and ThingSpeak

Added: 2026-05-31

[00:00:01]Let's make a smart temperature and humidity sensor that integrates automatically with Home Assistant and ThingSpeak.

[00:00:07]And you can build it in just half an hour.

[00:00:11]We start by printing the enclosure. Just drag and drop the STL files in your slicer.

[00:00:17]Then we move the top part and then we rotate it 180° along the Z axis.

[00:00:25]It's also important to not have supports enabled.

[00:00:31]And then we just check that everything is okay and we send it to the printer.

[00:00:38]Moving down onto the electronics, we use only two parts connected by four wires.

[00:00:43]The parts are ESP32-C3 Pro Mini board and an HTU21D sensor.

[00:00:51]We start by cutting the wires. We need four wires, two wires of 3.5 cm and two wires of 4 cm.

[00:01:00]Let's remove the wire insulation from the ends of the wires and tin them so that the final assembly will be easier.

[00:01:11]We remove the boards from their packaging bags and start soldering the wires. You can find in the video description links to the specific parts I used. Let's solder the wires on the ESP board according to the schematic.

[00:01:24]For perfect solder joints, I really recommend using flux.

[00:01:29]Now that we have the wires attached to the ESP32 board, we'll also solder them to the sensor board.

[00:01:36]Having all wires soldered, we just twist them several times.

[00:01:42]Electronics is done now, so we can just connect it to the USB to our computer.

[00:01:48]In order to flash the firmware, we need to use Chrome or Edge. We go to github.com/linemcu and select the temperature and humidity sensor repo.

[00:01:58]In the readme, there is a link to the web flash page. We click on it, click on connect and flash, and then we select USB JTAG serial debug unit.

[00:02:08]Then we click on install Lin MCU TH sensor, next, and install.

[00:02:25]Now, the firmware is installed on our sensor.

[00:02:31]The last step is to configure the sensor. We enter config mode by resetting the board and then quickly pressing the boot button until the blue LED starts flashing.

[00:02:44]At this point, the sensor created an access point to which we can connect.

[00:02:48]Normally, it opens automatically a web browser pointing to the setup page. If this does not happen, enter in your browser http://192.168.4.1.

[00:03:00]From the settings page, we choose configure Wi-Fi and we set the Wi-Fi credentials, the parameters, and the Home Assistant and ThingSpeak variables.

[00:03:21]Then, we click save.

[00:03:24]And if the Wi-Fi credentials were correct, all settings are saved in the non-volatile storage.

[00:03:32]And the grand finale is here. After configuration, the chip will reset and will automatically show up in Home Assistant. No YAML or any other configuration required. You only need the MQTT integration installed.

[00:03:48]The sensor showed up in the list of MQTT devices and the overview.

[00:03:58]If you want to use ThingSpeak, you need to create a channel and enable the first three fields being temperature, humidity, and RSSI.

[00:04:06]You will also need to provide the right API key of this channel in your sensor settings.

[00:04:12]Then, you'll start seeing the data being recorded.

[00:04:26]In the meantime, the enclosure was printed, so we can start the final assembly.

[00:04:43]One last finishing touch, if you don't like to see the power LED, we can get rid of it using a precision knife. We slowly cut away pieces of the LED until we see the blue board beneath.

[00:04:54]Subscribe to the channel if you want to see how you can build a very small smart motion sensor.