You must configure wifi network before adding the accessory to HomeKit. To configure Wi-Fi settings, device generates its own Wi-Fi in AP mode. You must connect to it in order to setup your Wi-Fi network.

Simply take your iOS device, go to Setting -> Wi-Fi, and search for an SSID called HomeKid- followed by the module's MAC address and connect to it. For security reasons the AP is password protected!

Wait a few seconds until a web appears showing you all Wi-Fi networks that the device has found. Select yours, and enter password then click the Join button! The module will try to connect the selected Wi-Fi network, this will take a couple of seconds.

Note: If the given password is wrong, you can Reset the Wi-fi settings by holding the Reset button for 10sec

In your iOS device, open Home App and follow normal steps to add a new accessory.
Pairing setup takes about 30 seconds.

Default  HomeKit code is 021-82-017.

Also You can scan this HomeKit QR code:

Note: If pairing fails, you can unpower your device, repower it, and start HomeKit setup again (Wifi settings keep configured)

I've added HomeKit Characteristic for detecting general fault.
If the BME280 doesn't work properly, HomeKit will nofify you about this problem!

The sensor works the same as an original Elgato EVE Degree.

To calibrate - for proper data - the barometric pressure based on your home's altitude, please download Elgato EVE app!

After successful pairing, find the Sensor, and click the Gear icon at the upper right corner and after this, click on Elevation tab. After that, click on Detect and go back to the main accessory page! EVE needs your location for these step! The Sensor will save this setting until you factory reset the module!

Other thing to mention is sadly HomeKit NOT supports barometric pressure at the moment, so you'll need 3rd party HomeKit apps (eg.: EVE) for reading these values!

The sensor can be setup with an SSD1306 OLED screen that using i2c bus connection and 128x64px resolution. Temperature Display Units can be changed between Celsius/Fahrenheit within Eve app.
The Barometric Pressure also will swicth to inHg instead of hPa!

A lot of people reported errors, weird text/images with the "correct" SSD1306 display, so i've dig deeper into the problem: Chinese stores are selling SH1106 as SSD1306 OLED displays, they look similar but the driver is not the same! Now both SSD1306 and SH1106 screens are supported. If you experiencing any weird text/image issues now you can triple press the button to change between SSD1306 and SH1106 display types, the ESP8266 will save the config and reboot with the correct setup and your display should work 😄 Default display type is SSD1306!

The code has a Reset function in case of something goes wrong. Wait about 5 seconds to allow device to boot completely, and then long press the button for at least 10sec!

All configured settings has been removed and device is restarting. This removes HomeKit and Wi-Fi settings, and your device will go to Access Point mode next time in order to reconfigure Wi-Fi.

If wifi network becomes unreachable, device will keep searching Wi-Fi automatically until it can connect again when Wi-Fi becomes available.

If your ESP8266 module doesn't have physical button attached, you can use jumper wires to connect GPIO0 and GND for 10 seconds.

Note: Resetting the accessory may not remove it from the Home app, you need to do it manually after resetting!